ORMLite

Version 6.1 – December 2021

ORMLite provides a lightweight Object Relational Mapping between Java classes and SQL databases. There are certainly more mature ORMs which provide this functionality including Hibernate and iBatis. However, the author wanted a simple yet powerful wrapper around the JDBC functions, and Hibernate and iBatis are significantly more complicated with many dependencies.

ORMLite supports JDBC connections to MySQL, Postgres, H2, SQLite, Derby, HSQLDB, Microsoft SQL Server, and can be extended to additional ones relatively easily. ORMLite also supports native database calls on Android OS. There are also initial implementations for DB2, Oracle, generic ODBC, and Netezza although the author needs access to an instance of each of these databases to tune the support. Contact the author if your database is not supported.

To get started quickly with ORMLite, see section Getting Started. Android users should also look at the Android specific pages. See section Using With Android. You can also take a look at the the examples section of the document which has various working code packages and Android applications. See section Example Code. There is also a PDF version of this documentation.

Gray Watson http://256stuff.com/gray/

1. Getting Started

The following information should help you to get started with ORMLite. Android users should also look at the Android specific page after reading these pages here. See section Using With Android.

1.1 Downloading ORMLite Jar

To get started with ORMLite, you will need to download the jar files. The ORMLite release page is the default repository but the jars are also available from the central maven repository and from Sourceforge.

Users that are connecting to SQL databases via JDBC connections will need to download the ormlite-jdbc-6.1.jar file. For use with Android applications, you should download the ormlite-android-6.1.jar file instead. ORMLite does not have any required external dependencies although there are some optional packages that you may want to use. See section External Dependencies. The code works with Java 5 or later.

1.2 Configuring a Class

The following is an example class that is configured to be persisted to a database using ORMLite annotations. The @DatabaseTable annotation configures the Account class to be persisted to the database table named accounts. The @DatabaseField annotations map the fields on the Account to the database columns with the same names.

The name field is configured as the primary key for the database table by using the id = true annotation field. Also, notice that a no-argument constructor is needed so the object can be returned by a query. For more information (JPA annotations and other ways to configure classes) see the class setup information later in the manual. See section Setting Up Your Classes.

@DatabaseTable(tableName = "accounts")
public class Account {
    
    @DatabaseField(id = true)
    private String name;
    @DatabaseField
    private String password;
    
    public Account() {
        // ORMLite needs a no-arg constructor 
    }
    public Account(String name, String password) {
        this.name = name;
        this.password = password;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

1.3 Configuring a DAO

A typical Java pattern is to isolate the database operations in Data Access Objects (DAO) classes. Each DAO provides create, delete, update, etc. type of functionality and specializes in the handling a single persisted class. A simple way to build a DAO is to use the createDao static method on the DaoManager class. For example, to create a DAO for the Account class defined above you would do:

Dao<Account, String> accountDao =
  DaoManager.createDao(connectionSource, Account.class);
Dao<Order, Integer> orderDao =
  DaoManager.createDao(connectionSource, Order.class);

More information about setting up the DAOs is available later in the manual. See section Setting Up the DAOs.

1.4 Code Example

This example uses the native Java H2 database to create an in-memory test database. You will need to download and add the H2 jar file to your classpath if you want to run the example as-is. See the H2 home page. NOTE: Android users should see the Android specific documentation later in the manual. See section Using With Android. There are also complete code examples that can be used. See section Example Code.

The code performs the following steps.

• It creates a connection source which handles connections to the database.
• It instantiates a DAO for the Account object.
• The accounts database table is created. This step is not needed if the table already exists.

public class AccountApp {

    public static void main(String[] args) throws Exception {

        // this uses h2 by default but change to match your database
        String databaseUrl = "jdbc:h2:mem:account";
        // create a connection source to our database
        ConnectionSource connectionSource =
            new JdbcConnectionSource(databaseUrl);

        // instantiate the dao
        Dao<Account, String> accountDao =
            DaoManager.createDao(connectionSource, Account.class);

        // if you need to create the 'accounts' table make this call
        TableUtils.createTable(connectionSource, Account.class);

Once we have configured our database objects, we can use them to persist an Account to the database and query for it from the database by its ID:

        // create an instance of Account
        Account account = new Account();
        account.setName("Jim Coakley");

        // persist the account object to the database
        accountDao.create(account);

        // retrieve the account from the database by its id field (name)
        Account account2 = accountDao.queryForId("Jim Coakley");
        System.out.println("Account: " + account2.getName());

        // close the connection source
        connectionSource.close();
    }
}

You should be able to get started using ORMLite by this point. To understand more of the functionality available with ORMLite, continue on with the next section. See section How to Use.

For more examples including working code and Android application projects see section Example Code.

2. How to Use

This chapter goes into more detail about how to use the various features in ORMLite.

2.1 Setting Up Your Classes

To setup your classes to be persisted you need to do the following things:

1. Add the @DatabaseTable annotation to the top of each class. You can also use @Entity.
2. Add the @DatabaseField annotation right before each field to be persisted. You can also use @Column and others.
3. Add a no-argument constructor to each class with at least package visibility.

2.1.1 Adding ORMLite Annotations

Annotations are special code markers have have been available in Java since version 5 that provide meta information about classes, methods, or fields. To specify what classes and fields to store in the database, ORMLite supports either its own annotations (@DatabaseTable and @DatabaseField) or the more standard annotations from the javax.persistence package. See section Using javax.persistence Annotations. Annotations are the easiest way to configure your classes but you can also configure the class using Java code or Spring XML. See section Class Configuration.

With ORMLite annotations, for each of the Java classes that you would like to persist to your SQL database, you will need to add the @DatabaseTable annotation right above the public class line. Each class marked with one of these annotations will be persisted into its own database table. For example:

@DatabaseTable(tableName = "accounts")
public class Account {
…

The @DatabaseTable annotations can have an optional tableName argument which specifies the name of the table that corresponds to the class. If not specified, the class name, with normalized case, is used by default. With the above example each Account object will be persisted as a row in the accounts table in the database. If the tableName was not specified, the account table would be used instead.

More advanced users may want to add a daoClass argument which specifies the class of the DAO object that will be operating on the class. This is used by the DaoManager to instantiate the DAO internally. See DaoManager.

Additionally, for each of the classes, you will need to add a @DatabaseField annotation to each of the fields in the class that are to be persisted to the database. Each field is persisted as a column of a database row. For example:

@DatabaseTable(tableName = "accounts")
public class Account {

    @DatabaseField(id = true)
    private String name;

    @DatabaseField(canBeNull = false)
    private String password;
    …

In the above example, each row in the accounts table has 2 columns:

• the name column which is a string and also is the database identity (id) of the row
• the password column, also a string which can not be null

The @DatabaseField annotation can have the following fields:

columnName

String name of the column in the database that will hold this field. If not set then the field name, with normalized case, is used instead.

dataType

The type of the field as the DataType class. Usually the type is taken from Java class of the field and does not need to be specified. This corresponds to the SQL type. See section Persisted Data Types.

defaultValue

String default value of the field when we are creating a new row in the table. Default is none.

width

Integer width of the field – mostly used for string fields. Default is 0 which means to take the data-type and database-specific default. For strings that means 255 characters although some databases do not support this.

canBeNull

Boolean whether the field can be assigned to null value. Default is true. If set to false then you must provide a value for this field on every object inserted into the database.

id

Boolean whether the field is the id field or not. Default is false. Only one field can have this set in a class. Id fields uniquely identity a row and are required if you want to use the query, update, refresh, and delete by ID methods. Only one of this, generatedId, and generatedIdSequence can be specified. See section Fields With id.

generatedId

Boolean whether the field is an auto-generated id field. Default is false. Only one field can have this set in a class. This tells the database to auto-generate a corresponding id for every row inserted. When an object with a generated-id is created using the Dao.create() method, the database will generate an id for the row which will be returned and set in the object by the create method. Some databases require sequences for generated ids in which case the sequence name will be auto-generated. To specify the name of the sequence use generatedIdSequence. Only one of this, id, and generatedIdSequence can be specified. See section Fields With generatedId.

generatedIdSequence

String name of the sequence number to be used to generate this value. Same as generatedId but you can specify the sequence name to use. Default is none. Only one field can have this set in a class. This is only necessary for databases which require sequences for generated ids. If you use generatedId instead then the code will auto-generate a sequence name. Only one of this, id, and generatedId can be specified. See section Fields With generatedIdSequence.

foreign

Boolean setting which identifies this field as corresponding to another class that is also stored in the database. Default is false. The field must not be a primitive type. The other class must have an id field (either id, generatedId, or generatedIdSequence) which will be stored in this table. When an object is returned from a query call, any foreign objects will just have the id field set. See section Foreign Object Fields.

useGetSet

Boolean that says that the field should be accessed with get and set methods. Default is false which instead uses direct field access via Java reflection. This may be necessary if the object you are storing has protections around it.

NOTE: The name of the get method must match getXxx() where Xxx is the name of the field with the first letter capitalized. The get must return a class which matches the field’s exactly. The set method must match setXxx(), have a single argument whose class matches the field’s exactly, and return void. For example:

@DatabaseField(useGetSet = true) private Integer orderCount; public Integer getOrderCount() { return orderCount; } public void setOrderCount(Integer orderCount) { this.orderCount = orderCount; }

unknownEnumName

If the field is a Java enumerated type then you can specify the name of a enumerated value which will be used if the value of a database row is not found in the enumerated type. If this is not specified and a database row does contain an unknown name or ordinal value then a SQLException is thrown when the row is being read from the database. This is useful to handle backwards compatibility when handling out-of-date database values as well as forwards compatibility if old software is accessing up-to-date data or if you have to roll a release back.

throwIfNull

Boolean that tells ORMLite to throw an exception if it sees a null value in a database row and is trying to store it in a primitive field. By default it is false. If it is false and the database field is null, then the value of the primitive will be set to 0 (false, null, etc.). This can only be used on a primitive field.

persisted

Set this to be false (default true) to not store this field in the database. This is useful if you want to have the annotation on all of your fields but turn off the writing of some of them to the database.

format

This allows you to specify format information of a particular field. Right now this is only applicable for a couple of types including:

• DATE_STRING for specifying the format of the date string stored in the database
• STRING_BYTES for specifying the Charset used to encode the string as an array of bytes
• BOOLEAN_CHAR for specifying characters representing the true and false values in the database.

unique

Adds a constraint to the table so that this field that it has to be unique across all rows in the table. For example, you might have an Account class which has a generated account-id but you also want the email address to be unique across all Accounts. If more than one field is marked as unique in a table, then each of the fields by themselves must be unique. For example, if you have the firstName and lastName fields, both with unique=true and you have "Bob", "Smith" in the database, you cannot insert "Bob", "Jones" nor "Kevin", "Smith".

To have more than 1 field that are each unique in combination, see the uniqueCombo setting. You can also use the uniqueIndexName to create an index for this field.

uniqueCombo

Adds a constraint to the table so that a combination of all fields that have uniqueCombo set to true has to be unique across all rows in the table. For example, if you have the firstName and lastName fields, both with uniqueCombo=true, and you have "Bob", "Smith" in the database, you cannot insert another "Bob", "Smith" but you can insert "Bob", "Jones" and "Kevin", "Smith".

To have fields be unique by themselves, see the unique setting. You can also use the uniqueIndexName to create an index for this field.

index

Boolean value (default false) to have the database add an index for this field. This will create an index with the name columnName with a "_idx" suffix. To specify a specific name of the index or to index multiple fields, use the indexName field.

uniqueIndex

Boolean value (default false) to have the database add a unique index for this field. Same as index but this will ensure that all of the values in the index are unique. If you just want to make sure of unique-ness then you can use the unique field instead.

indexName

String value (default none) to have the database add an index for this field with this name. You do not need to specify the index boolean as well. To index multiple fields together in one index, each of the fields should have the same indexName value.

uniqueIndexName

String value (default none) to have the database add a unique index for this field with this name. Same as index but this will ensure that all of the values in the index are unique. For example, this means that you can insert ("pittsburgh", "pa") and ("harrisburg", "pa") and ("pittsburgh", "tx") but not another ("pittsburgh", "pa").

foreignAutoRefresh

Set this to be true (default false) to have a foreign field automagically refreshed when an object is queried. The default is to just have the ID field in the object retrieved and for the caller to call refresh on the correct DAO. If this is set to true then, when the object is queried, a separate database call will be made to load of the fields of the foreign object via an internal DAO. NOTE: this will not automagically create the foreign object if you create an object that has this field set.

NOTE: This will create another DAO object internally so low memory devices may want to call refresh by hand.

NOTE: To protect against recursion, there are a couple of places were auto-refreshing has been limited. If you are auto-refreshing a class that itself has field with foreignAutoRefresh set to true or if you are auto-refreshing a class with a foreign collection, in both cases the resulting field will be set to null and not auto-refreshed. You can always call refresh on the field directly if you need it.

NOTE: If you have an auto-refreshed field that is an object that also has an auto-refreshed field, you may want to tune the maxForeignAutoRefreshLevel value. See below.

maxForeignAutoRefreshLevel

This can be used to set the maximum number of levels to configure foreign objects. For example, if you have a Question which has an foreign field of the best Answer, and the Answer has an foreign field to the corresponding question, then the configuration back and forth can get large. This is especially a problem with auto-refreshed fields when you lookup the Question it could cause an infinite loop. By default, ORMLite only goes through 2 levels but you can decrease it to 1 (0 is not valid) or increase it. The higher the number the more database transactions happen when you load in your Question.

In our example, the foreign fields in Question and Answer could be set to auto-refresh. If this is true then with the maxForeignAutoRefreshLevel set to 1, when you query for a Question, the Answer field will be auto-refreshed, but the Question field on the answer will only have its id field set. It will not be auto-refreshed.

allowGeneratedIdInsert

If this is set to true (default is false) then inserting an object with the ID field already set will not override it with a generated-id. This is useful when you have a table where you are inserting items that sometimes have IDs and sometimes need them generated. This only works if the database supports this behavior and if generatedId is also true for the field.

columnDefinition

If this is set with a string then it will be used to define the column in the CREATE TABLE statement. By default the database type is used to auto-generate the SQL necessary to create the column. The column name is provided by ORMLite. For example:

@DatabaseField(columnDefinition = "LONGBLOB not null", dataType = DataType.BYTE_ARRAY) public byte[] bigBunchOfBytes;

If you need to specify the full schema definition including the name, see fullColumnDefinition below.

foreignAutoCreate

Set this to be true (default false) to have the foreign field automatically created using an internal DAO if its ID field is not set (null or 0). So when you call dao.create() on the parent object, any foreign field that has this set to true will possibly generate an additional create call via an internal DAO. By default you have to create the object using its DAO directly. By default you have to create the object using its DAO directly. This only works if generatedId is also set to true.

// the account field in Order has foreignAutoCreate=true Order order1 = new Order(); // account1 has not been created in the db yet, id field is null order1.account = account1; // this will create order1 in the order table _and_ // pass order1.account to the internal accountDao.create(). orderDao.create(order1);

version

Set this to true (default false) to have this field be a version for the row. A version field adds restrictions when an object is updated to the datbase that protects against data corruption when multiple entities are updating the row at the same time. This is very useful in distributed database scenarios if (for example) a utility process is updating an Account and you don’t want to protect against overwriting a user update from the web-server.

1. The current-value of the version field is read from the object
2. The update statement is augmented with a "WHERE version = current-value"
3. The new-value being updated in the database is changed by ORMLite to be the current-value + 1 or the current java.util.Date
4. If the row has been updated by another entity then the update will not change the database since the current-value will not match the version column in the database and 0 rows changed will be returned by the update method
5. However, if the current-value does match the version field in the database then the row will be updated, the object’s version field will be set by ORMLite to the new-value, 1 will be returned from update

Only the following field types are appropriate for version fields: short, integer, long, and Date fields. Date can also be stored as a string (dataType = DataType.DATE_STRING) or long (dataType = DataType.DATE_LONG).

NOTE: If you define a Date field to be a version then you can also use it as a modification time on the row. When the object is created in the database, the version field will be automatically inserted with the current Date. When the object is updated, the version field will be updated with the current Date. Something like the following works well (the dataType=... is optional):

@DatabaseField(version = true, dataType = DataType.DATE_LONG) private Date lastModified;

foreignColumnName

Name of the foreign object’s field that is tied to this table. This does not need to be specified if you are using the ID of the foreign object which is recommended. For example, if you have an Order object with a foreign Account then you may want to key off of the Account name instead of the ID.

NOTE: Setting this implies foreignAutoRefresh is also set to true because there is no way to refresh the object since the id field is not stored in the database. So when this is set, the field will be automatically refreshed in another database query.

readOnly

Set this to be true (default false) if this field is a read-only field. This field will be returned by queries however it will be ignored during insert/create statements. This can be used to represent create or modification dates with the values being generated by the database. You should specify the specific schema to create those dates via the columnDefinition setting.

foreignColumnName

Specify the SQL necessary to create this field in the database including the column name, which should be properly escaped and in proper case depending on your database type. This can be used if you need to fully describe the schema to enable some per-database feature or to override the default SQL generated. If you just need to specify the schema for a column then the columnDefinition should be used instead.

2.1.2 Using javax.persistence Annotations

Instead of using the ORMLite annotations (see section Adding ORMLite Annotations), you can use the more standard JPA annotations from the javax.persistence package. In place of the @DatabaseTable annotation, you can use the javax.persistence @Entity annotation. For example:

@Entity(name = "accounts")
public class Account {
…

The @Entity annotations can have an optional name argument which specifies the table name. If not specified, the class name with normalized case is used by default.

Instead of using the @DatabaseField annotation on each of the fields, you can use the javax.persistence annotations: @Column, @Id, @GeneratedValue, @OneToOne, @ManyToOne, @JoinColumn, and @Version. For example:

@Entity(name = "accounts")
public class Account {

    @Id
    private String name;

    @Column(nullable = false)
    private String password;
    …

The following javax.persistence annotations and fields are supported:

@Entity

Specifies that the class is stored in the database.

name

Used to specify the name of the associated database table. If not provided then the class name is used.

@Column

Specifies the field to be persisted to the database. You can also just specify the @Id annotation. The following annotation fields are supported, the rest are ignored.

name

Used to specify the name of the associated database column. If not provided then the field name is taken.

length

Specifies the length (or width) of the database field. Maybe only applicable for Strings and only supported by certain database types. Default for those that do is 255. Same as the width field in the @DatabaseField annotation.

nullable

Set to true to have a field be able to be inserted into the database with a null value. Same as the canBeNull field in the @DatabaseField annotation.

unique

Adds a constraint to the field that it has to be unique across all rows in the table. Same as the unique field in the @DatabaseField annotation.

@Id

Used to specify a field to be persisted to the database as a primary row-id. If you want to have the id be auto-generated, you will need to also specify the @GeneratedValue annotation.

@GeneratedValue

Used to define an id field as having a auto-generated value. This is only used in addition to the @Id annotation. See the generatedId field in the @DatabaseField annotation for more details.

@OneToOne or @ManyToOne

Fields with these annotations are assumed to be foreign fields. See section Foreign Object Fields. ORMLite does not enforce the many or one relationship nor does it use any of the annotation fields. It just uses the existence of either of these annotations to indicate that it is a foreign object.

@JoinColumn

name

Sets the column name of the field. Same as @Column{name=...}.

nullable

Set to true to have a field be able to be inserted into the database with a null value. Same as @Column{nullable=...}.

@Version

Using this annotation will turn short, integer, long, and Date fields into a version field. See version field.

If the @Column annotation is used on a field that has a unknown type then it is assumed to be a Serializable type field and the object should implement java.io.Serializable. See datatype serializable.

2.1.3 Adding a No-Argument-Constructor

After you have added the class and field annotations, you will also need to add a no-argument constructor with at least package visibility. When an object is returned from a query, ORMLite constructs the object using Java reflection and a constructor needs to be called.

Account() {
    // all persisted classes must define a no-arg constructor
    // with at least package visibility
}

So your final example Account class with annotations and constructor would look like:

@DatabaseTable(tableName = "accounts")
public class Account {
    
    @DatabaseField(id = true)
    private String name;
    
    @DatabaseField(canBeNull = false)
    private String password;
    …

    Account() {
        // all persisted classes must define a no-arg constructor
        // with at least package visibility
    }
    …
}

2.2 Persisted Data Types

The following Java types can be persisted to the database by ORMLite. Database specific code helps to translate between the SQL types and the database specific handling of those types. See section Database Specific Code.

String (DataType.STRING)

Persisted as SQL type VARCHAR.

String (DataType.LONG_STRING)

Persisted as SQL type LONGVARCHAR which handles longer strings.

String (DataType.STRING_BYTES)

A Java String persisted as an array of bytes (byte[]) with the SQL type VARBINARY. Many databases are Unicode compliant (MySQL/Postgres) but some are not (SQLite). To store strings with accents or other special characters, you may have to encode them as an array of bytes using this type. By default the Unicode Charset is used to convert the string to bytes and back again. You can use the format field in DatabaseField to specify a custom character-set to use instead for the field. Comparison and ordering of this type may not be possible depending on the database type.

boolean or Boolean (DataType.BOOLEAN or DataType.BOOLEAN_OBJ)

Persisted as SQL type BOOLEAN.

boolean or Boolean (DataType.BOOLEAN or DataType.BOOLEAN_OBJ) as a character

Persisted as SQL type BOOLEAN.

boolean or Boolean (DataType.BOOLEAN or DataType.BOOLEAN_OBJ) as an integer

Persisted as SQL type INTEGER. False is 0 and every other value is true.

byte or Byte (DataType.BYTE or DataType.BYTE_OBJ)

Persisted as SQL type TINYINT.

byte array (DataType.BYTE_ARRAY)

Array of bytes (byte[]) persisted as SQL type VARBINARY. This is different from the DataType.SERIALIZABLE type which serializes an object as an array of bytes.

NOTE: Because of backwards compatibility, any fields that are of type byte[] must be specified as DataType.BYTE_ARRAY or DataType.SERIALIZABLE using the dataType field and will not be auto-detected. See DatabaseField dataType.

@DatabaseField(dataType = DataType.BYTE_ARRAY) byte[] imageBytes;

char or Character (DataType.CHAR or DataType.CHAR_OBJ)

Persisted as SQL type CHAR.

NOTE: If you are using Derby you should consider using a String instead since comparisons of character fields are not allowed.

short or Short (DataType.SHORT or DataType.SHORT_OBJ)

Persisted as SQL type SMALLINT.

int or Integer (DataType.INTEGER or DataType.INTEGER_OBJ)

Persisted as SQL type INTEGER.

long or Long (DataType.LONG or DataType.LONG_OBJ)

Persisted as SQL type BIGINT.

float or Float (DataType.FLOAT or DataType.FLOAT_OBJ)

Persisted as SQL type FLOAT.

double or Double (DataType.DOUBLE or DataType.DOUBLE_OBJ)

Persisted as SQL type DOUBLE.

Serializable (DataType.SERIALIZABLE)

Persisted as SQL type VARBINARY. This is a special type that serializes an object as a sequence of bytes and then de-serializes it on the way back. The field must be an object that implements the java.io.Serializable interface. Depending on the database type, there will be limits to the size of the object that can be stored. This is different from the DataType.BYTE_ARRAY type which stores the byte array directly.

Some databases place restrictions on this field type that it cannot be the id column in a class. Other databases do not allow you to query on this type of field at all. If your database does support it, you may also have to use a Select Argument to query for this type. See section Using Select Arguments.

NOTE: To use this type, you must specify DataType.SERIALIZABLE using the dataType field. It will not be auto-detected. See DatabaseField dataType.

// image is an object that implements Serializable @DatabaseField(dataType = DataType.SERIALIZABLE) Image image;

enum or Enum (DataType.ENUM_NAME)

Persisted by default as the enumerated value’s string name as a VARCHAR type. The string name is the default (and recommended over ENUM_INTEGER) because it allows you to add additional enums anywhere in the list without worrying about having to convert data later. Formerly called ENUM_STRING.

You can also also specify an unknownEnumName name with the @DatabaseField annotation which will be used if an unknown value is found in the database. See unknownEnumName.

enum or Enum (DataType.ENUM_TO_STRING)

Similar to ENUM_STRING but this is persisted by default as the value from the enum’s toString() method as opposed to its name as a VARCHAR type.

enum or Enum (DataType.ENUM_INTEGER)

You specify the dataType field (from the @DatabaseField annotation) as a DataType.ENUM_INTEGER in which case the ordinal of the enum value will be stored as an INTEGER. The name (ENUM_NAME) is the default (and recommended) because it allows you to add additional enums anywhere in the list without worrying about having to convert data later. If you insert (or remove) an enum from the list that is being stored as a number, then old data will be un-persisted incorrectly.

You can also also specify an unknownEnumName name with the @DatabaseField annotation which will be used if an unknown value is found in the database. See unknownEnumName.

UUID (DataType.UUID)

The java.util.UUID class persisted as a VARCHAR type. It saves it as the uuid.toString() and used the UUID.fromString(String) method to convert it back again. You can also mark a UUID field as being generated-id in which case whenever it is inserted, java.util.UUID.randomUUID() is called and set on the field. See section Fields With generatedId.

UUID (DataType.UUID_NATIVE)

You specify the dataType field (from the @DatabaseField annotation) as a DataType.UUID_NATIVE to persist a UUID in a database native column format. This is only supported by a couple of different database types and is still inserted with JDBC as a string.

BigInteger (DataType.BIG_INTEGER)

The java.math.BigInteger class persisted as a VARCHAR type. It is saved using the bigInteger.toString() and uses the string constructor to convert it back again.

BigDecimal (DataType.BIG_DECIMAL)

The java.math.BigDecimal class persisted as a VARCHAR type. It is saved using the bigDecimal.toString() and uses the string constructor to convert it back again.

BigDecimal (DataType.BIG_DECIMAL_NUMERIC)

You specify the dataType field (from the @DatabaseField annotation) as a DataType.BIG_DECIMAL_NUMERIC in which case a java.math.BigDecimal field will be persisted as a NUMERIC type. This is only supported by some database types and with various default precision settings. Android should use the default DataType.BIG_DECIMAL.

java.util.Date (DataType.DATE)

Persisted as SQL type TIMESTAMP. This type automatically uses an internal ? argument because the string format of it is unreliable to match the database format. See section Using Select Arguments. See also DATE_LONG and DATE_STRING.

NOTE: This is a different class from java.sql.Date which is handled by DataType.SQL_DATE.

NOTE: Certain databases only provide seconds resolution so the milliseconds will be 0.

java.util.Date (DataType.DATE_LONG)

You can also specify the dataType field to the @DatabaseField annotation as a DataType.DATE_LONG in which case the milliseconds value of the Date will be stored as an LONG. See also DATE and DATE_STRING.

NOTE: This is a different class from java.sql.Date which is handled by DataType.SQL_DATE.

NOTE: Certain databases only provide seconds resolution so the milliseconds will be 0.

java.util.Date (DataType.DATE_INTEGER)

Persisted as SQL type INTEGER. This stores the date as integer seconds since epoch.

java.util.Date (DATE_STRING)

You can also specify the dataType field to the @DatabaseField annotation as a DataType.DATE_STRING in which case the date will be stored as a string in yyyy-MM-dd HH:mm:ss.SSSSSS format. You can use the format field in DatabaseField to set the date to another format. See also DATE and DATE_LONG.

NOTE: This is a different class from java.sql.Date which is handled by DataType.SQL_DATE.

NOTE: Certain databases only provide seconds resolution so the milliseconds will be 0.

org.joda.time.DateTime (DataType.DATE_TIME)

This stores the Joda DateTime into the database as long epoch millis. This persister uses reflection to avoid setting up a dependency with Joda jars. You can define a custom data persister if you want to natively use the class. See custom data persister.

java.sql.Date (DataType.SQL_DATE)

Persisted as SQL type TIMESTAMP.

NOTE: This is the java.sql.Date and not the java.util.Date. It is recommended that you use the java.util.Date class handled by DataType.DATE instead.

java.sql.Timestamp (DataType.TIME_STAMP)

Persisted as SQL type TIMESTAMP.

NOTE: It is recommended that you use the java.util.Date class instead which is the DataType.DATE type.

java.sql.Timestamp (DataType.TIME_STAMP_STRING)

Persisted as SQL type TIMESTAMP.

You can also specify the dataType field to the @DatabaseField annotation as a DataType.TIME_STAMP_STRING in which case the date will be stored as a string in yyyy-MM-dd HH:mm:ss.SSSSSS format. You can use the format field in DatabaseField to set the time-stamp to another format.

NOTE: It is recommended that you use the java.util.Date class instead which is the DataType.DATE_STRING type. See also DATE_STRING.

java.util.Currency (DataType.CURRENCY)

Persisted as SQL type STRING.

NOTE: ORMLite also supports the concept of foreign objects where the id of another object is stored in the database. See section Foreign Object Fields.

2.3 Connection Sources

NOTE: With regards to connection sources, Android users should see the Android specific documentation later in the manual. See section Using With Android.

To use the database and the DAO objects, you will need to configure what JDBC calls a DataSource (see the javax.sql.DataSource class) and what ORMLite calls a ConnectionSource. A ConnectionSource is a factory for connections to the physical SQL database. Here is a code example that creates a simple, single-connection source.

// single connection source example for a database URI
ConnectionSource connectionSource =
  new JdbcConnectionSource("jdbc:h2:mem:account");

The package also includes the class JdbcPooledConnectionSource which is a relatively simple implementation of a pooled connection source. As database connections are released, instead of being closed, they are added to an internal list so they can be reused at a later time. New connections are created on demand only if there are no dormant connections available. JdbcPooledConnectionSource is also synchronized and can be used by multiple threads. It has settings for the maximum number of free connections before they are closed as well as a maximum age before a connection is closed.

// pooled connection source
JdbcPooledConnectionSource connectionSource =
  new JdbcPooledConnectionSource("jdbc:h2:mem:account");
// only keep the connections open for 5 minutes
connectionSource.setMaxConnectionAgeMillis(5 * 60 * 1000);

JdbcPooledConnectionSource also has a keep-alive thread which pings each of the dormant pooled connections every so often to make sure they are valid – closing the ones that are no long good. You can also enable the testing of the connection right before you get a connection from the pool. See the javadocs for more information.

// change the check-every milliseconds from 30 seconds to 60
connectionSource.setCheckConnectionsEveryMillis(60 * 1000);
// for extra protection, enable the testing of connections
// right before they are handed to the user
connectionSource.setTestBeforeGet(true);

There are many other, external data sources that can be used instead, including more robust and probably higher-performance pooled connection managers. You can instantiate your own directly and wrap it in the DataSourceConnectionSource class which delegates to it.

// basic Apache data source
BasicDataSource dataSource = new BasicDataSource();
String databaseUrl = "jdbc:h2:mem:account";
dataSource.setUrl(databaseUrl);
// we wrap it in the DataSourceConnectionSource
ConnectionSource connectionSource = 
  new DataSourceConnectionSource(dataSource, databaseUrl);

When you are done with your ConnectionSource, you will want to call a close() method to close any underlying connections. Something like the following pattern is recommended.

JdbcConnectionSource connectionSource =
    new JdbcPooledConnectionSource("jdbc:h2:mem:account");
try {
    // work with the data-source and DAOs
    …
} finally {
    connectionSource.close();
}

Unfortunately, the DataSource interface does not have a close method so if you are using the DataSourceConnectionSource you will have to close the underlying DataSource by hand – the close() method on the DataSourceConnectionSource does nothing.

2.4 Setting Up the DAOs

Once you have annotated your classes and defined your ConnectionSource you will need to create the Data Access Object (DAO) class(es), each of which will handle all database operations for a single persisted class. Each DAO has two generic parameters: the class we are persisting with the DAO, and the class of the ID-column that will be used to identify a specific database row. If your class does not have an ID field, you can put Object or Void as the 2nd argument. For example, in the above Account class, the "name" field is the ID column (id = true) so the ID class is String.

The simplest way to create your DAO is to use the createDao static method on the DaoManager class to create a DAO class. For example:

Dao<Account, String> accountDao =
  DaoManager.createDao(connectionSource, Account.class);
Dao<Order, Integer> orderDao =
  DaoManager.createDao(connectionSource, Order.class);

NOTE: You should use the DaoManager.createDao() method to create your DAO classes so if they are needed by internal ORMLite functionality, they can be reused and not regenerated. Building a DAO can be an expensive operation and for devices with limited resources (like mobile apps), DAOs should be reused if at all possible.

If you want a better class hierarchy or if you need to add additional methods to your DAOs, you should consider defining an interface which extends the Dao interface. The interface isn’t required but it is a good pattern so your code is less tied to JDBC for persistence. The following is an example DAO interface corresponding to the Account class from the previous section of the manual:

/** Account DAO which has a String id (Account.name) */
public interface AccountDao extends Dao<Account, String> {
    // empty wrapper, you can add additional DAO methods here
}

Then in the implementation, you should extend the BaseDaoImpl base class. Here’s the example implementation of your DAO interface.

/** JDBC implementation of the AccountDao interface. */
public class AccountDaoImpl extends BaseDaoImpl<Account, String>
  implements AccountDao {
    // this constructor must be defined
    public AccountDaoImpl(ConnectionSource connectionSource)
      throws SQLException {
        super(connectionSource, Account.class);
    }
}

To make use of your custom DAO classes, you need to add the daoClass field to the @DatabaseTable on the corresponding entity class:

@DatabaseTable(daoClass = AccountDaoImpl.class)
public class Account {
   …
}

That’s all you need to define your DAO classes. You are free to add more methods to your DAO interfaces and implementations if there are specific operations that are needed and not provided by the Dao base classes. More on how to use these DAOs later. See section DAO Usage.

NOTE: If you are using a custom DAO then be sure to add the daoClass argument to the @DatabaseTable annotation which specifies the class of your custom DAO. This is used by the DaoManager to instantiate the DAO internally. See DaoManager.

2.5 Supported Databases

ORMLite supports the following database flavors. Some of them have some specific documentation that needs to be obeyed.

MySQL

Tables are created in MySQL with the InnoDB engine by default using CREATE TABLE ... ENGINE=InnoDB. If you want to use another engine, you can instantiate the MysqlDatabaseType directly and use the setCreateTableSuffix() method to use the default or another engine. Also, MySQL does some funky stuff with the last-modification time if a Date is defined as a TIMESTAMP so DATETIME was used instead.

Postgres

No special instructions.

H2

No special instructions. We use this database for all of our internal testing with in-memory and small on-disk databases.

SQLite

There are multiple SQLite drivers out there. Make sure you use the Xerial driver and not the Zentus driver which does not support generated ids.

If you want to use the internal SQLite time/date functions (such as strftime) on Date fields, your fields should be of type DATE_STRING to have the dates match in the internal date formats. For example:

@DatabaseField(dataType = DataType.DATE_STRING) private Date date;

Android SQLite

Android’s SQLite database is accessed through direct calls to the Android database API methods.

Derby

There are two drivers for Derby: one embedded and one client/server. ORMLite makes an attempt to detect the right driver but you may have to set the right database type on your ConnectionSource directly if it doesn’t. See section Database Specific Code.

HSQLDB

No special instructions.

Microsoft SQL Server

No special instructions.

Netezza

There is some support for Netezza although it should be considered beta and possibly with bugs. I do not currently have access to a server running a Netezza database. We will try to keep this driver up to date with the help of contributors. Thanks to Richard Kooijman for the driver. Please contact us if you want to help with development of this driver.

ODBC

There also some support for ODBC although it should be considered beta and possibly with bugs. I do not have access to a server running Microsoft’s Open Database Connectivity. We will try to keep this driver up to date with the help of contributors. Thanks to Dale Asberry for the driver. Please contact us if you want to help with development of this driver.

DB2

I do not have access to an DB2 database so we cannot run any tests to make sure that our support for it works well. Please contact us if you want to help with development of this driver.

Oracle

I do not have access to an Oracle database so we cannot run any tests to make sure that our support for it works well. Please contact us if you want to help with development of this driver.

Please contact the author if your database is not supported.

2.6 Tying It All Together

So you have annotated the objects to be persisted, added the no-argument constructor, created your ConnectionSource, and defined your DAO classes. You are ready to start persisting and querying your database objects. You will need to download and add the H2 jar file to your class-path if you want to run the example as-is. See the H2 home page.

The following code ties it all together:

// h2 by default but change to match your database
String databaseUrl = "jdbc:h2:mem:account";
JdbcConnectionSource connectionSource =
  new JdbcConnectionSource(databaseUrl);

// instantiate the dao with the connection source
AccountDaoImpl accountDao = new AccountDaoImpl(connectionSource);

// if you need to create the 'accounts' table make this call
TableUtils.createTable(connectionSource, Account.class);

// create an instance of Account
Account account = new Account("Jim Coakley");

// persist the account object to the database
accountDao.create(account);
…

// destroy the data source which should close underlying connections
connectionSource.destroy();

For more examples, see the code later in the manual. See section Example Code.

2.7 Table and Schema Creation

There a couple of tools that ORMLite provides to help with creating tables and schema for the classes that you are storing in the database.

2.7.1 TableUtils Class

The TableUtils class provides a number of static methods that help with creating and dropping tables as well as providing the schema statements.

createTable(ConnectionSource, Class)

This method takes the ConnectionSource and a class and creates the table associated with the class. It uses the annotations from the class to determine the various fields and characteristics of the table. It returns the number of statements executed to create the table.

TableUtils.createTable(connectionSource, Account.class);

createTableIfNotExists(ConnectionSource, Class)

Similar to the last method but it will only create the table if it doesn’t exist. This is not supported on all database types.

createTable(ConnectionSource, DatabaseTableConfig)

Similar to the last method but instead of a class, this method uses a DatabaseTableConfig to determine the various fields and characteristics of the table.

ArrayList<DatabaseFieldConfig> fieldConfigs = new ArrayList<DatabaseFieldConfig>(); fieldConfigs.add(new DatabaseFieldConfig("id", null, DataType.UNKNOWN, null, 0, false, false, true, null, false, null, false, null, false, null, false, null, null, false)); … DatabaseTableConfig<Account> tableConfig = new DatabaseTableConfig<Account>(Account.class, fieldConfigs); // this returns number of statements executed to create table TableUtils.createTable(connectionSource, tableConfig);

createTableIfNotExists(ConnectionSource, DatabaseTableConfig)

Similar to the last method but it will only create the table if it doesn’t exist. This is not supported on all database types.

dropTable(ConnectionSource, Class, boolean ignoreErrors)

This method drops the table associated with the class. It uses the annotations from the class to determine the name of the table to drop. This is not undo-able and most likely will be used only in tests since production tables are dropped rarely.

The ignoreErrors argument is useful when you are dropping a table before you are creating it and the table may not already exist. If ignoreErrors is true then any exceptions are swallowed.

dropTable(ConnectionSource, DatabaseTableConfig, boolean ignoreErrors)

Same as the previous method but it will use the DatabaseTableConfig to determine the name of the table to drop.

getCreateTableStatements(ConnectionSource, Class)

This is similar to the createTable method but will return a list of statements that can be used to create a class. This is useful if you want to load the schema during some sort of database initialization process.

getCreateTableStatements(ConnectionSource, DatabaseTableConfig)

Same as the previous method but with a DatabaseTableConfig instead.

clearTable(ConnectionSource, Class)

Clear all data out of the table. For certain database types and with large sized tables, which may take a long time. In some configurations, it may be faster to drop and re-create the table. This is [obviously] very destructive and is unrecoverable.

clearTable(ConnectionSource, DatabaseTableConfig)

Same as the previous method but with a DatabaseTableConfig instead.

2.7.2 TableCreator Class

The TableCreator class is engineered for use with Spring but could be useful in other configurations. It is configured with the ConnectionSource and the list of DAOs that are being used by the program.

It will automagically create the tables associated with those DAOs if the system property ormlite.auto.create.tables is set with the value "true". It also will automagically drop the tables that were created if the system property ormlite.auto.drop.tables is set with the value "true". This is especially useful in tests when you are starting with a test database that needs to get the latest schema but in production you want to make specific schema changes by hand. You can set the system properties in your test start scripts but leave them off in the production scripts.

List<Dao<?, ?>> daoList = new ArrayList<Dao<?, ?>>();
daoList.add(accountDao);
…

TableCreator creator =
   new TableCreator(connectionSource, daoList);
// create the tables if the right system property is set
creator.maybeCreateTables();
…

// later, we may want to drop the tables that were created 
creator.maybeDropTables();

For a real life example of using TableCreator you can see spring example.

2.8 Identity Columns

Database rows can be identified by a particular column which is defined as the identity column. Rows do not need to have an identity column but many of the DAO operations (update, delete, refresh) require an identity column. The identity can either be supplied by the user or auto-generated by the database. Identity columns have unique values for every row in the table and they must exist if you want to query-by-id, delete, refresh, or update a particular row using the DAO. To configure a field as an identity field, you should use one (and only one) of the following three settings from @DatabaseField: id, generatedId, or generatedIdSequence.

2.8.1 Fields With id

With our Account example class, the string name field has been marked with id = true. This means that the name is the identity column for the object. Each account stored in the database must have a unique value for the name field – you cannot have two rows with the name "John Smith".

public class Account {
    @DatabaseField(id = true)
    private String name;
    …
}

When you use the DAO to lookup an account with a particular name, you will use the identity field to locate the Account object in the database:

Account account = accountDao.queryForId("John Smith");
if (account == null) {
    // the name "John Smith" does not match any rows
}

NOTE: If you need to change the value of an object’s id field, you must use the Dao.updateId() method which takes the current object still with its old id value and the new value. ORMLite has to first locate the object by its old id and then update it with the new id. See updateId.

2.8.2 Fields With generatedId

You can configure a long or integer field to be a generated identity column. The id number column for each row will then be automatically generated by the database.

public class Order {
    @DatabaseField(generatedId = true)
    private int id;
    …
}

When an Order object is passed to create and stored to the database, the generated identity value is returned by the database and set on the object by ORMLite. In the majority of database types, the generated value starts at 1 and increases by 1 every time a new row is inserted into the table.

// build our order object without an id
Order order = new Order("Jim Sanders", 12.34);
…
orderDao.create(order);
System.out.println("Order id " + order.getId() +
   " was persisted to the database");
// query for the order with an id of 1372
order = orderDao.queryForId(1372);
if (order == null) {
   // none of the order rows have an id of 1372
}

In the above code example, an order is constructed with name and amount (for example). When it is passed to the DAO’s create method, the id field has not been set. After it has been saved to the database, the generated-id will be set on the id field by ORMLite and will be available when getId() is called on the order after the create method returns.

NOTE: Other special field types such as UUID can also be generated. See UUID.

NOTE: You can use the allowGeneratedIdInsert field setting to allow insert objects into a table with or without an id already set. See allowGeneratedIdInsert.

NOTE: Depending on the database type, you may not be able to change the value of an auto-generated id field.

2.8.3 Fields With generatedIdSequence

Some databases use what’s called a sequence number generator to provide the generated id value. If you use generatedId = true with those databases, a sequence name will be auto-generated by ORMLite. If, however, you need to set the name of the sequence to match existing schema, you can used the generatedIdSequence value which takes a string name for the sequence.

public class Order {
    @DatabaseField(generatedIdSequence = "order_id_seq")
    private int id;
    …
}

In the above example, the id value is again automatically generated but using a sequence with the name order_id_seq. This will throw an exception if you are working with a database which does not support sequences.

NOTE: Depending on the database type, you may not be able to change the value of an auto-generated id field.

2.9 DAO Usage

The following database operations are easily accomplished by using the DAO methods:

create and persist an object to the database

This inserts a new row to the database table associated with the object.

Account account = new Account(); account.name = "Jim Coakley"; accountDao.create(account);

query for it’s id column

If the object has an id field defined by the annotations, then we can lookup an object in the database using its id.

Account account = accountDao.queryForId(name); if (account == null) { account not found handling … }

update the database row associated with the object

If you change fields in an object in memory, you must call update to persist those changes to the database. This requires an id field.

account.password = "_secret"; accountDao.update(account);

refreshing an object if the database has changed

If some other entity has changed a row the database corresponding to an object in memory, you will need to refresh that object to get the memory object up-to-date. This requires an id field.

accountDao.refresh(account);

delete the account from the database

Removes the row that corresponds to the object from the database. Once the object has been deleted from the database, you can continue to use the object in memory but any update or refresh calls will most likely fail. This requires an id field.

accountDao.delete(account);

iterate through all of the rows in a table:

The DAO is also an iterator so you can easily run through all of the rows in the database:

// page through all of the accounts in the database for (Account account : accountDao) { System.out.println(account.getName()); }

NOTE: you must page through all items for the iterator to close the underlying SQL object. If you don’t go all of the way through to the loop, ORMLite does not know to close the underlying object, and a connection to the database may be leaked that will only be closed if the garbage collector reaps some time later which may cause bugs in your code. Use the try ... finally wrapped iterator patterns below.

For example, the following for loop is a very bad pattern.

for (Account account : accountDao) { if (account.getName().equals("Bob Smith")) { // you can't return, break, or throw from here return account; } }

This also may happen if an exception is thrown out of the loop so for loops should not be used in these cases. This is also the case with lazy loaded collections. See lazy collection iterator.

use the iterator directly

You can also use the iterator directly because the for loops are not optimal. This allows you to use try ... finally which is a much better pattern.

CloseableIterator<Account> iterator = accountDao.closeableIterator(); try { while (iterator.hasNext()) { Account account = iterator.next(); System.out.println(account.getName()); } } finally { // close it at the end to close underlying SQL statement iterator.close(); }

get a "wrapped iterable"

You can also use the "wrapped iterable" which allows you to do the close in the finally while still using for loops.

CloseableWrappedIterable<Account> wrappedIterable = accountDao.getWrappedIterable(); try { for (Account account : wrappedIterable) { … } } finally { wrappedIterable.close(); }

For a detailed list of the methods in the DAO see section DAO Methods.

2.10 Indexing Fields

ORMLite provides some limited support for indexing of various fields in your data classes. First off, it is important to point out that any field marked as an id field is already indexed. Fields that are id fields do not need to have additional indexes built and if they are specified, errors may result with certain database.

To add an index on a non-id field, all you need to do is add the index = true boolean field to the @DatabaseField annotation. See index. This will create a non-unique index after the table is created for the field and will drop the index if the table is then dropped. Indexes help optimize queries and can significantly improve times on queries to medium to large sized tables.

public class Account {
    @DatabaseField(id = true)
    private String name;
    // this indexes the city field so queries on city
    // will go faster for large tables
    @DatabaseField(index = true)
    private String city;
    …
}

This example creates the index account_city_idx on the Account table. If you want to use a different name, you can use the indexName = "othername" field instead which allows you to specify the name of the index.

If you often query on (for example) city and state fields together, you might want to create an index on both fields. ORMLite supports creating indexes on multiple fields by specifying the same indexName value for each of the fields you want to be included in the index.

@DatabaseField(indexName = "account_citystate_idx")
private String city;
@DatabaseField(indexName = "account_citystate_idx")
private String state;

This example will create one index for both the city and state fields. Note that queries on the city by itself will not be optimized – only queries on both city and state will be. With some databases, it may be better to create a single field index on each field and let the database use both indexes if you are querying on city and state. For other databases, creating an index on multiple fields is recommended. You may need to experiment and use the SQL EXPLAIN command to pinpoint how your database is utilizing your indexes.

To create unique indexes, there is a uniqueIndex = true and uniqueIndexName = "othername" fields also available on the @DatabaseField annotation. These work the same as the above settings but will instead create unique indexes that ensure that no two row has the same value(s) for the indexed field(s).

2.11 Issuing Raw SQL Statements

In a number of instances, using the defined DAO functionality may not be enough to change your database. For this reason, ORMLite has calls which allow you to issue raw query, update, and execute statements to the database.

2.11.1 Issuing Raw Queries

The built-in methods available in the Dao interface and the QueryBuilder classes don’t provide the ability to handle all types of queries. For example, aggregation queries (sum, count, avg, etc.) cannot be handled as an object since every query has a different result list. To handle these queries, you can issue raw database queries using the queryRaw methods on DAO. These methods return a GenericRawResults object which represents a result as an array of strings, array of objects, or user mapped objects. See the documentation on the GenericRawResults object for more details on how to use it, or take a look at the following examples.

// find out how many orders account-id #10 has
GenericRawResults<String[]> rawResults =
  orderDao.queryRaw(
    "select count(*) from orders where account_id = 10");
// there should be 1 result
List<String[]> results = rawResults.getResults();
// the results array should have 1 value
String[] resultArray = results.get(0);
// this should print the number of orders that have this account-id
System.out.println("Account-id 10 has " + resultArray[0] + " orders");

You can even use the QueryBuilder to build the raw queries for you if you’d lile using the prepareStatementString() method. See section Query Builder Basics.

QueryBuilder<Account, Integer> qb = accountDao.queryBuilder();
qb.where().ge("orderCount", 10);
results = accountDao.queryRaw(qb.prepareStatementString());

If you want to use the QueryBuilder with arguments to the raw query then you should do something like:

QueryBuilder<Account, Integer> qb = accountDao.queryBuilder();
// we specify a SelectArg here to generate a ? in statement string below
qb.where().ge("orderCount", new SelectArg());
// the 10 at the end is an optional argument to fulfill SelectArg above
results = accountDao.queryRaw(qb.prepareStatementString(), 10);

If you want to use the QueryBuilder with aggregate or other raw/custom arguments do something like the following. Since there is only one result out you can use the genericRawResults.getFirstResult() method:

QueryBuilder<Account, Integer> qb = accountDao.queryBuilder();
// select 2 aggregate functions as the return
qb.selectRaw("MIN(orderCount)", "MAX(orderCount)");
// the results will contain 2 string values for the min and max
results = accountDao.queryRaw(qb.prepareStatementString());
String[] values = results.getFirstResult();

For large numbers of results, you should consider using the iterator() method on the GenericRawResults object which uses database paging. For example:

// return the orders with the sum of their amounts per account
GenericRawResults<String[]> rawResults =
  orderDao.queryRaw(
    "select account_id,sum(amount) from orders group by account_id");
// page through the results
for (String[] resultArray : rawResults) {
  System.out.println("Account-id " + resultArray[0] + " has "
    + resultArray[1] + " total orders");
}
rawResults.close();

If you are just trying to query for a single value (typically an aggregate function like MAX) then you can use the queryRawValue(...) method:

long maxUnits = orderDao.queryRawValue("select max(units) from orders");

If some of your fields cannot be appropriately mapped to strings, you can also return the fields as an Object[] if you pass in the types of the resulting columns. For example:

// return the orders with the sum of their amounts per account
GenericRawResults<Object[]> rawResults =
  orderDao.queryRaw(
    "select account_id,sum(amount) from orders group by account_id",
    new DataType[] { DataType.LONG, DataType.INTEGER });
// page through the results
for (Object[] resultArray : rawResults) {
  System.out.println("Account-id " + resultArray[0] + " has "
    + resultArray[1] + " total orders");
}
rawResults.close();

NOTE: select * can return fields in different orders depending on the database type. To make sure that the data-type array matches the returned columns you must specify the fields specifically and not with a SQL *.

You can also map the results into your own object by passing in a RawRowMapper object. This will call the mapping object with an array of strings and allow it to convert the strings into an object. The DAO provides a default RawRowMapper that can be gotten from orderDao.getRawRowMapper() that knows how to convert the string array into the object.

You can also define your own custom mapper if the results are more complex. For example:

// return the orders with the sum of their amounts per account
GenericRawResults<Foo> rawResults =
  orderDao.queryRaw(
    "select account_id,sum(amount) from orders group by account_id",
    new RawRowMapper<Foo>() {
            public Foo mapRow(String[] columnNames,
              String[] resultColumns) {
                return new Foo(Long.parseLong(resultColumns[0]),
                    Integer.parseInt(resultColumns[1]));
        }
    });
// page through the results
for (Foo foo : rawResults) {
  System.out.println("Account-id " + foo.accountId + " has "
    + foo.totalOrders + " total orders");
}
rawResults.close();

NOTE: The query and the resulting strings can be very database-type specific. For example:

1. Certain databases need all column names specified in uppercase – others need lowercase.
2. You may have to quote your column or table names if they are reserved words.
3. The resulting column names also could be uppercase or lowercase again depending on the database type.
4. select * can return fields in a different order than you expect.

NOTE: Like other ORMLite iterators, you will need to make sure you iterate through all of the results to have the statement closed automatically. You can also call the rawResults.close() method to make sure the iterator, and any associated database connections, is closed.

NOTE: If you are using the QueryBuilder#prepareStatementString() method to build your query, the QueryBuild may have added the id column to the selected column list if the Dao object has an id you did not include it in the columns you selected. This means that your results may have one more column than you are expecting.

Another way that you can map the results is by using a DatabaseResultsMapper object. This will call the mapping object with the internal DatabaseResults object to map a row and output an object. If you are using this with JDBC, then you you can case the DatabaseResults to be a JdbcDatabaseResults. This will give you access to the JdbcDatabaseResults.getResultSet() method and the underlying JDBC result object. For example:

// return the orders with the sum of their amounts per account
GenericRawResults<Foo> rawResults =
  orderDao.queryRaw(
    "select account_id,sum(amount) from orders group by account_id",
    new RawRowMapper<Foo>() {
            public Foo mapRow(DatabaseResults results) {
                ResultSet resultSet = 
                   ((JdbcDatabaseResults)results).getResultSet();
                // now you can use the ResultSet to build Foo
                …
        }
    });
// page through the results
for (Foo foo : rawResults) {
  System.out.println("Account-id " + foo.accountId + " has "
    + foo.totalOrders + " total orders");
}
rawResults.close();

2.11.2 Issuing Raw Update Statements

You can also issue raw update statements against the database if the DAO functionality does not give you enough flexibility. Update SQL statements must contain the reserved words INSERT, DELETE, or UPDATE. For example:

fooDao.updateRaw("INSERT INTO accountlog (account_id, total) "
   + "VALUES ((SELECT account_id,sum(amount) FROM accounts))

2.11.3 Issuing Raw Execute Statements

You can also issue raw update statements against the database if the DAO functionality does not give you enough flexibility. For example:

fooDao.executeRaw("ALTER TABLE accountlog DROP COLUMN partner");

2.12 Foreign Object Fields

ORMLite supports the concept of "foreign" objects where one or more of the fields correspond to an object are persisted in another table in the same database. For example, if you had an Order objects in your database and each Order had a corresponding Account object, then the Order object would have foreign Account field. With foreign objects, just the id field from the Account is persisted to the Order table as the column "account_id". For example, the Order class might look something like:

@DatabaseTable(tableName = "orders")
public class Order {

    @DatabaseField(generatedId = true)
    private int id;
    
    @DatabaseField(canBeNull = false, foreign = true)
    private Account account;
    …
}

When the Order table was created, something like the following SQL would be generated:

CREATE TABLE `orders`
   (`id` INTEGER AUTO_INCREMENT , `account_id` INTEGER,
    PRIMARY KEY (`id`)); 

Notice that the name of the field is not account but is instead account_id. You will need to use this field name if you are querying for it. You can set the column name using the columnName field in the DatabaseField annotation. See columnName.

When you are creating a field with a foreign object, please note that the foreign object will not automatically be created for you. If your foreign object has a generated-id which is provided by the database then you need to create it before you create any objects that reference it. For example:

Account account = new Account("Jim Coakley");
accountDao.create(account);
// this will create the account object and set any generated ids

// now we can set the account on the order and create it
Order order = new Order("Jim Sanders", 12.34);
order.setAccount(account);
…
orderDao.create(order);

If you want some level of auto creation, then you can use the foreignAutoCreate setting. See foreignAutoCreate.

When you query for an order, you will get an Order object with an account field object that only has its id field set. The rest of the fields in the foreign Account object will have default values (null, 0, false, etc.). If you want to use other fields in the Account, you must call refresh on the accountDao class to get the Account object filled in. For example:

Order order = orderDao.queryForId(orderId);
System.out.println("Account-id on the order should be set: " +
   order.account.id);
// this should print null for order.account.name
System.out.println("But other fields on the account should not be set: "
   + order.account.name);

// so we refresh the account using the AccountDao
accountDao.refresh(order.getAccount());
System.out.println("Now the account fields will be set: " +
   order.account.name);

You can have the foreign objects automagically refreshed by using the foreignAutoRefresh setting. See foreignAutoRefresh.

NOTE: Because we use refresh, foreign objects are therefor required to have an id field.

You can query for foreign fields in a couple of different ways. The following examples show code which queries for all orders that match a certain account field. Since the id field is the name field, you can query by the name field of the account:

// query for all orders that match a certain account
List<Order> results =
  orderDao.queryBuilder().where().
    eq("account_id", account.getName()).query();

Or you can just let ORMLite extract the id field from the account itself. This will perform an equivalent query to the above:

// ORMLite will extract and use the id field internally
List<Order> results =
  orderDao.queryBuilder().where().
    eq("account_id", account).query();

There is example code to show how to use foreign objects. See foreign objects example.

2.13 Foreign Collections

In the above section of the manual we gave the example of the Order class having a foreign object field to the Account table. A foreign collection allows you to add a collection of orders on the account table. Whenever an Account object is returned by a query or refreshed by the DAO, a separate query is made over the order table and a collection of orders is set on the account. All of the orders in the collection have a corresponding foreign object that matches the account. For example:

public class Account {
    …
    @ForeignCollectionField(eager = false)
    ForeignCollection<Order> orders;
    …
}

In the above example, the @ForeignCollectionField annotation marks that the orders field is a collection of the orders that match the account. The field type of orders must be either ForeignCollection<T> or Collection<T> – no other collections are supported because they are much heavier with many methods to support. The @ForeignCollectionField annotation supports the following fields:

eager

There are two different types of foreign collections: eager or lazy. If eager is set to true then the separate query is made immediately and the orders are stored as a list within the collection. If eager is set to false (the default) then the collection is considered to be "lazy" and will iterate over the database using the Dao.iterator() only when a method is called on the collection.

WARNING: By default, if you have eager collections of objects that themselves have eager collections, the inner collection will be created as lazy for performance reasons. If you need change this see the maxEagerLevel setting below.

maxEagerLevel

This can be set to the number of times to expand an eager foreign collection’s foreign collection. If you query for A and it has an eager foreign-collection of field B which has an eager foreign-collection of field C (…), then a lot of database operations are going to happen whenever you query for A. By default this value is 1 meaning that if you query for A, the collection of B will be eager fetched but each of the B objects will have a lazy collection instead of an eager collection of C. It should be increased only if you know what you are doing.

columnName

The name of the column. This is only used if you want to match the string passed to Dao.assignEmptyForeignCollection(Object, String) or to specify that you want the collection returned when you specify queryBuilder.selectColumns(...). See selectColumns.

orderColumnName

The name of the column in the foreign object that we should order the collection by.

orderAscending

If an order column has been defined with the above orderColumnName, this sets the order as ascending (true which is the default) or descending (false).

foreignFieldName

Name of the field (not the column name) in the class that the collection is holding that corresponds to the collection. This is needed if there are two foreign fields in the class in the collection (such as a tree structure) and you want to identify which column you want in this collection.

WARNING: Due to some internal complexities, this it field/member name in the class and not the column-name.

Remember that when you have a ForeignCollection field, the class in the collection must (in this example Order) must have a foreign field for the class that has the collection (in this example Account). If Account has a foreign collection of Orders, then Order must have an Account foreign field. It is required so ORMLite can find the orders that match a particular account.

WARNING: With lazy collections, even the size() method causes a iteration across the database. You’ll most likely want to just use the iterator() and toArray() methods on lazy collections.

NOTE: Like with the Dao.iterator() method, the iterator returned by a lazy collection must be closed when you are done with it because there is a connection open to the database underneath. A close happens either if you go all of the way through the iterator or if you call close() on it. Only the ForeignCollection returns a closeable iterator. This means that for loops across lazy loaded collections are a bad pattern. For more details about iterating across lazy collections, see the iterator documentation. See iterator.

The foreign collections support the add() and remove() methods in which case the objects will be both added or removed from the internal list if the collection is eager, and DAO calls will be made to affect the order table as well for both eager and lazy collections.

NOTE: When you are adding a new object to a foreign collection, this will also add it to the database by calling through to dao.create(obj). If the object has already been created in the database then you should instead set the foreign field on the object and call dao.update(obj). If you add it here the DAO will try to create it in the database again which will most likely cause an error.

NOTE: When you call update on an object with a foreign collection (like Account above) the objects that are stored in the collection are not automatically written to the database as well. There is no way for ORMLite to be able to detect which of the objects has been updated unfortunately. If you update an object in the collection you should call the update(data) method on the ForeignCollection to make sure that the object is persisted. For example:

for (Order order : account.orders()) {
   // if we are changing some field in the order
   order.setAmount(123);
   // then we need to update it in the database
   account.orders.update(order);
}

Lastly, there is example code to show how to use foreign collections. See foreign collections example.

2.14 DAO Enabled Objects

Another ORM pattern is to have the objects perform the database operations on themselves instead of using a Database Access Object (DAO). For example, given a data object foo, you would call foo.refresh() instead of fooDao.refresh(foo). The default pattern is to use the Dao classes which allow your data classes to have their own hierarchy and it isolates the database code in the Daos. However, you are free to use the BaseDaoEnabled class if you prefer this pattern.

All classes that are able to refresh (update, delete, etc.) themselves should extend the BaseDaoEnabled class. For example:

@DatabaseTable(tableName = "accounts")
public class Account extends BaseDaoEnabled {

    @DatabaseField(id = true)
    private String name;

    @DatabaseField(canBeNull = false)
    private String password;
    …

To first create the object, you will need to use the DAO object or you will need to set the dao on the object so that it can self create:

account.setDao(accountDao);
account.create();

However, whenever an object is returned by ORMLite as query results, the DAO has already been set on the object it extends the BaseDaoEnabled class.

Account account = accountDao.queryForId(name);
account.setPassword(newPassword);
account.update();

This will also work for foreign fields.

Order order = orderDao.queryForId(orderId);
// load all of the fields from the account
order.getAccount().refresh();

The javadocs for BaseDaoEnabled will have the most up-to-date list of self operations but right now the class can do:

create

To create the object you will need to use the DAO or to call setDao() on the object.

refresh

Refresh the object in case it was updated in the database.

update

After you make changes to the object in memory, update it in the database.

updateId

If you need to update the id of the object, you must use this method. You cannot change the id field in the object and then call the update method because then the object will not be found.

delete

Delete it from the database.

Feedback on this is welcome.

3. Custom Statement Builder

The DAOs have methods to query for an object that matches an id field (queryForId), query for all objects (queryForAll), iterating through all of the objects in a table (iterator), and some other simple martching methods. However, for more custom queries, there is the queryBuilder() method which returns a QueryBuilder object for the DAO with which you can construct custom queries to return a sub-set of your tables.

3.1 Query Builder Basics

Here’s how you use the query builder to construct custom queries. First, it is a good pattern to set the column names of the fields with Java constants so you can use them in queries. For example:

@DatabaseTable(tableName = "accounts")
public class Account {
    public static final String PASSWORD_FIELD_NAME = "password"; 
    
    …
    @DatabaseField(canBeNull = false, columnName = PASSWORD_FIELD_NAME)
    private String password;
    …

This allows us to construct queries using the password field name without having the renaming of a field in the future break our queries. This should be done even if the name of the field and the column name are the same.

// get our query builder from the DAO
QueryBuilder<Account, String> queryBuilder =
  accountDao.queryBuilder();
// the 'password' field must be equal to "qwerty"
queryBuilder.where().eq(Account.PASSWORD_FIELD_NAME, "qwerty");
// prepare our sql statement
PreparedQuery<Account> preparedQuery = queryBuilder.prepare();
// query for all accounts that have "qwerty" as a password
List<Account> accountList = accountDao.query(preparedQuery);

You get a QueryBuilder object from the Dao.queryBuilder() method, call methods on it to build your custom query, call queryBuilder.prepare() which returns a PreparedQuery object, and then pass the PreparedQuery to the DAO’s query or iterator methods.

As a short cut, you can also call the prepare() method on the Where object to do something like the following:

// query for all accounts that have that password
List<Account> accountList =
   accountDao.query(
      accountDao.queryBuilder().where()
         .eq(Account.PASSWORD_FIELD_NAME, "qwerty")
         .prepare());

You can use another short cut to call query() or iterator() either on the QueryBuilder or Where objects.

// query for all accounts that have that password
List<Account> accountList =
      accountDao.queryBuilder().where()
         .eq(Account.PASSWORD_FIELD_NAME, "qwerty")
         .query();

3.2 Building Queries

There are a couple of different ways that you can build queries. The QueryBuilder has been written for ease of use as well for power users. Simple queries can be done linearly:

QueryBuilder<Account, String> queryBuilder =
  accountDao.queryBuilder();
// get the WHERE object to build our query
Where<Account, String> where = queryBuilder.where();
// the name field must be equal to "foo"
where.eq(Account.NAME_FIELD_NAME, "foo");
// and
where.and();
// the password field must be equal to "_secret"
where.eq(Account.PASSWORD_FIELD_NAME, "_secret");
PreparedQuery<Account> preparedQuery = queryBuilder.prepare();

The SQL query that will be generated from the above example will be approximately:

SELECT * FROM account
  WHERE (name = 'foo' AND password = '_secret')

If you’d rather chain the methods onto one line (like StringBuilder), this can also be written as:

queryBuilder.where()
  .eq(Account.NAME_FIELD_NAME, "foo")
  .and()
  .eq(Account.PASSWORD_FIELD_NAME, "_secret");

If you’d rather use parenthesis to group the comparisons properly then you can call:

Where<Account, String> where = queryBuilder.where();
where.and(where.eq(Account.NAME_FIELD_NAME, "foo"),
          where.eq(Account.PASSWORD_FIELD_NAME, "_secret"));

All three of the above call formats produce the same SQL. For complex queries that mix ANDs and ORs, the last format may be necessary to get the grouping correct. For example, here’s a complex query:

Where<Account, String> where = queryBuilder.where();
where.or(
  where.and(
    where.eq(Account.NAME_FIELD_NAME, "foo"),
    where.eq(Account.PASSWORD_FIELD_NAME, "_secret")),
  where.and(
    where.eq(Account.NAME_FIELD_NAME, "bar"),
    where.eq(Account.PASSWORD_FIELD_NAME, "qwerty")));

This produces the following approximate SQL:

SELECT * FROM account
  WHERE ((name = 'foo' AND password = '_secret')
         OR (name = 'bar' AND password = 'qwerty'))

If you want to do complex queries linearly, you can even use Reverse Polish Notation (of all things). There is a Where.or(int) and Where.and(int) methods which do the operation on the previous number of specified clauses.

where.eq(Account.NAME_FIELD_NAME, "foo");
where.eq(Account.PASSWORD_FIELD_NAME, "_secret");
// this does an AND between the previous 2 clauses
// it also puts a clause back on the stack
where.and(2);
where.eq(Account.NAME_FIELD_NAME, "bar"),
where.eq(Account.PASSWORD_FIELD_NAME, "qwerty")));
// this does an AND between the previous 2 clauses
// it also puts a clause back on the stack
where.and(2);
// this does an OR between the previous 2 AND clauses
where.or(2);

The QueryBuilder also allows you to set what specific select columns you want returned, specify the ’ORDER BY’ and ’GROUP BY’ fields, and various other SQL features (LIKE, IN, >, >=, <, <=, <>, IS NULL, DISTINCT, …). See section Where Capabilities. You can also see the javadocs on QueryBuilder and Where classes for more information. Here’s a good SQL reference site.

3.3 Building Statements

The DAO can also be used to construct custom UPDATE and DELETE statements. Update statements are used to change certain fields in rows from the table that match the WHERE pattern – or update all rows if no where(). Delete statements are used to delete rows from the table that match the WHERE pattern – or delete all rows if no where().

For example, if you want to update the passwords for all of the Accounts in your table that are currently null to the string "none", then you might do something like the following:

UpdateBuilder<Account, String> updateBuilder =
  accountDao.updateBuilder();
// update the password to be "none"
updateBuilder.updateColumnValue("password", "none");
// only update the rows where password is null
updateBuilder.where().isNull(Account.PASSWORD_FIELD_NAME);
updateBuilder.update();

With update, you can also specify the update value to be an expression:

// update hasDog boolean to true if dogC > 0
updateBuilder.updateColumnExpression(
  "hasDog", "dogC > 0");

To help you construct your expressions, you can use the UpdateBuilder’s escape methods escapeColumnName and escapeValue can take a string or a StringBuilder. This will protect you if columns or values are reserved words.

If, instead, you wanted to delete the rows in the Accounts table whose password is currently null, then you might do something like the following:

DeleteBuilder<Account, String> deleteBuilder =
  accountDao.deleteBuilder();
// only delete the rows where password is null
deleteBuilder.where().isNull(Account.PASSWORD_FIELD_NAME);
deleteBuilder.delete();

3.4 QueryBuilder Capabilities

The following are some details about the various method calls on the QueryBuilder object which build custom select, delete, and update statements. See the Javadocs for the QueryBuilder class for the most up-to-date information about the available methods. Most of these methods return the QueryBuilder object so they can be chained.

Here’s a good tutorial of SQL commands.

distinct()

Add "DISTINCT" clause to the SQL query statement.

NOTE: Use of this means that the resulting objects may not have a valid ID column value so cannot be deleted or updated.

groupBy(String columnName)

This adds a "GROUP" clause to the SQL query statement for the specified column name. This can be called multiple times to group by multiple columns.

NOTE: Use of this means that the resulting objects may not have a valid ID column value so cannot be deleted or updated.

groupByRaw(String sql)

Add a raw SQL "GROUP BY" clause to the SQL query statement. This allows you to group by things that are not just column names. The SQL argument should not include the "GROUP BY" string.

having(String sql)

Add a raw SQL "HAVING" clause to the SQL query statement. This allows you to apply filters after the WHERE and other matching has been completed. This is usually done with aggregate functions. The SQL argument should not include the "HAVING" string.

join(QueryBuilder joinedQueryBuilder)

Join with another query builder. This will add into the SQL something close to "INNER JOIN other-table ...". Either the object associated with the current query builder or the argument query builder must have a foreign field of the other one. An exception will be thrown otherwise. This can be called multiple times to join with more than one table.

leftJoin(QueryBuilder joinedQueryBuilder)

Same as join(QueryBuilder) but it will use "LEFT JOIN" instead. See: LEFT JOIN SQL documentation.

NOTE: RIGHT and FULL JOIN SQL commands are not supported because we are only returning objects from the "left" table.

limit(Integer maxRows)

Limit the output to maxRows maximum number of rows. Set to null for no limit (the default).

offset(Integer startRow)

Start the output at this row number. Set to null for no offset (the default). If you are paging through a table, you should consider using the Dao.iterator() method instead which handles paging with a database cursor. Otherwise, if you are paging you probably want to specify a column to orderBy.

NOTE: This is not supported for all databases. Also, for some databases, the limit must also be specified since the offset is an argument of the limit.

orderBy(String columnName, boolean ascending)

Add "ORDER BY" clause to the SQL query statement to order the results by the specified column name. Use the ascending boolean to get a ascending or descending order. This can be called multiple times to group by multiple columns.

orderByNullsFirst(String columnName, boolean ascending)

Add "ORDER BY" clause to the SQL query statement with a column-name and ascending (if true) with a NULLS FIRST qualifier. This may not be supported by all database types.

orderByNullsLast(String columnName, boolean ascending)

Add "ORDER BY" clause to the SQL query statement with a column-name and ascending (if true) with a NULLS LAST qualifier. This may not be supported by all database types.

orderByRaw(String sql)

Add a raw SQL "ORDER BY" clause to the SQL query statement. This allows you to order by things that are not just columns but can include calculations. The SQL argument should not include the "ORDER BY" string.

prepare()

Build and return a prepared query that can be used by Dao.query(PreparedQuery) or Dao.iterator(PreparedQuery) methods. If you change the where or make other calls you will need to re-call this method to re-prepare the statement for execution.

selectColumns(String... columns)

Add columns to be returned by the SELECT query and set on any resulting objects. If no columns are selected then all columns are returned by default. For classes with id columns, the id column is added to the select list automagically. All fields not selected in the object with be their default values (null, 0, false, etc.).

This allows you to in effect have lazy loaded fields. You can specify exactly which fields to be set on the resulting objects. This is especially helpful if you have large fields in a table that you don’t always want to access. To get all of the fields on the object later, you can either do another query or call refresh() with the object. This can be called multiple times to add more columns to select.

WARNING: If you specify any columns to return, then any foreign-collection fields will be returned as null unless their ForeignCollectionField.columnName is also in the list. See ForeignCollectionField.

selectColumns(Iterable<String> columns)

Same as the above but with an iterable (such as a collection) instead of a variable list of column names. This can be called multiple times to add more columns to select.

selectRaw(String... columns)

Add raw columns or aggregate functions (COUNT, MAX, ...) to the query. This will turn the query into something only suitable for using as a raw query. This can be called multiple times to add more columns to select. See section Issuing Raw Queries.

where()

Build and return the Where object with which you can customize your WHERE SQL statements. See section Where Capabilities.

query()

Convenience method to perform the query. Same as dao.query(queryBuilder.prepare()).

queryForFirst()

Convenience method to perform the query and return the first result. Same as dao.queryForFirst(queryBuilder.prepare()).

queryRawFirst()

Convenience method to perform a raw query on the generated state and then return the first result as a String[]. Same as Dao.queryRaw(String) and GenericRawResults.getFirstResult().

iterator()

Convenience method to generate the iterator for the query. Same as dao.iterator(queryBuilder.prepare()).

reset()

Resets all of the settings in the QueryBuilder so it can be reused.

3.5 Where Capabilities

The following are some details about the various method calls for adding WHERE SQL statements to your custom select, delete, and update statements. See the Javadocs for the Where class for the most up-to-date information about the available methods. All of the methods return the Where object so you can chain them together.

Here’s a good tutorial of SQL commands.

and()

Binary AND operation which takes the previous clause and the next clause and AND’s them together. This is when you are using inline query calls.

and(Where<T, ID> first, Where<T, ID> second, Where<T, ID>... others)

AND operation which takes 2 or more arguments and AND’s them together. This is when you are not using inline query calls but instead want to use standard arguments.

NOTE: There is no guarantee of the order of the clauses that are generated in the final query.

NOTE: There is an annoying code warning that I get with the usage of this method with more than 2 arguments that can be ignored.

and(int numClauses)

This method needs to be used carefully. This will absorb a number of clauses that were registered previously with calls to Where.eq() or other methods and will string them together with AND’s. There is no way to verify the number of previous clauses so the programmer has to count precisely.

NOTE: There is no guarantee of the order of the clauses that are generated in the final query.

between(String columnName, Object low, Object high)

Add a BETWEEN clause which makes sure the column is between the low and high parameters.

eq(String columnName, Object value)

Add a ’=’ clause which makes sure the column is equal to the value.

exists(QueryBuilder<?, ?> subQueryBuilder)

Add a EXISTS clause with a sub-query inside of parenthesis. This will return returns as long as the inner query returns results.

NOTE: The sub-query will be prepared at the same time that the outside query is.

ge(String columnName, Object value)

Add a ’>=’ clause which makes sure the column is greater-than or equals-to the value.

gt(String columnName, Object value)

Add a ’>’ clause which makes sure the column is greater-than the value.

idEq(ID id)

Add a clause where the ID is equals to the argument.

idEq(Dao<OD, ?> dataDao, OD data)

Add a clause where the ID is extracted from an existing object.

in(String columnName, Iterable<?> objects)

Add a IN clause which makes sure the column is equal-to one of the objects from the Iterable passed in. Most likely the Iterable should probably be on of the Collection classes such as a List or Set.

in(String columnName, Object... objects)

Add a IN clause which makes sure the column is equal-to one of the objects passed in.

in(String columnName, QueryBuilder<?, ?> subQueryBuilder)

Add a IN clause which makes sure the column is in one of the columns returned from a sub-query inside of parenthesis. The QueryBuilder must return 1 and only one column which can be set with the QueryBuilder.selectColumns(String...) method calls. That 1 argument must match the SQL type of the column-name passed to this method. See also Building Join Queries.

NOTE: The sub-query will be prepared at the same time that the outside query is.

isNull(String columnName)

Add a ’IS NULL’ clause which makes sure the column’s value is null. ’=’ NULL does not work.

isNotNull(String columnName)

Add a ’IS NOT NULL’ clause so the column must not be null. ’<>’ NULL does not work.

le(String columnName, Object value)

Add a ’<=’ clause which makes sure the column is less-than or equals-to the value.

lt(String columnName, Object value)

Add a ’<’ clause which makes sure the column is less-than the value.

like(String columnName, Object value)

Add a LIKE clause which makes sure the column match the value using ’%’ patterns.

ne(String columnName, Object value)

Add a ’<>’ clause which makes sure the column is not-equal-to the value.

not()

Used to NOT the next clause specified when using inline query calls.

not(Where<T, ID> comparison)

Used to NOT the argument clause specified. This is when you are not using inline query calls but instead want to use standard arguments.

notIn(String columnName, Iterable<?> objects)

Same as the IN clause but negated. Results are returned that are not in the objects from the iterator.

in(String columnName, Object... objects)

Same as IN clause but negated. Results are returned that are not in the variable array of objects.

notIn(String columnName, QueryBuilder<?, ?> subQueryBuilder)

Same as IN clause but negated. Results are returned that are not in the results from the sub-query.

or()

Binary OR operation which takes the previous clause and the next clause and OR’s them together. This is when you are using inline query calls.

or(Where<T, ID> first, Where<T, ID> second, Where<T, ID>... others)

OR operation which takes 2 or more arguments and OR’s them together. This is when you are not using inline query calls but instead want to use standard arguments.

NOTE: There is no guarantee of the order of the clauses that are generated in the final query.

NOTE: There is an annoying code warning that I get with the usage of this method with more than 2 arguments that can be ignored.

or(int numClauses)

This method needs to be used carefully. This will absorb a number of clauses that were registered previously with calls to Where.eq() or other methods and will string them together with OR’s. There is no way to verify the number of previous clauses so the programmer has to count precisely.

raw(String rawStatement)

Add a raw statement as part of the WHERE that can be anything that the database supports. Using the more structured methods above is recommended but this gives more control over the query and allows you to utilize database specific features.

prepare()

A short-cut for calling prepare() on the original QueryBuilder.prepare(). This method returns a PreparedQuery object.

reset()

Reset the where object so it can be reused in a new query but with the same QueryBuilder.

query()

Convenience method to perform the query. Same as queryBuilder.query() and dao.query(queryBuilder.prepare()).

queryRaw()

Convenience method to perform the query and return raw results. Same as queryBuilder.queryRaw() and dao.queryRaw(...).

queryForFirst()

Convenience method to perform the query and return the first result. Same as queryBuilder.queryForFirst() and dao.queryForFirst(queryBuilder.prepare()).

queryRawFirst()

Convenience method to perform the query and return the first raw result. Same as queryBuilder.queryRawFirst() and dao.queryRaw(...).

countOf()

Convenience method to perform the query and return the number of results. Same as queryBuilder.countOf() and dao.countOf(queryBuilder.prepare()).

iterator()

Convenience method to generate the iterator for the query. Same as queryBuilder.iterator() and dao.iterator(queryBuilder.prepare()).

3.6 Using Select Arguments

Select Arguments are arguments that are used in WHERE operations can be specified directly as value arguments (as in the above examples) or as a SelectArg object. SelectArgs are used to set the value of an argument at a later time – they generate a SQL ’?’.

For example:

QueryBuilder<Account, String> queryBuilder =
  accountDao.queryBuilder();
Where<Account, String> where = queryBuilder.where();
SelectArg selectArg = new SelectArg();
// define our query as 'name = ?'
where.eq(Account.NAME_FIELD_NAME, selectArg);
// prepare it so it is ready for later query or iterator calls
PreparedQuery<Account> preparedQuery = queryBuilder.prepare();

// later we can set the select argument and issue the query
selectArg.setValue("foo");
List<Account> accounts = accountDao.query(preparedQuery);
// then we can set the select argument to another
// value and re-run the query
selectArg.setValue("bar");
accounts = accountDao.query(preparedQuery);

It is a common problem for people to try to build queries or other statements with arguments that contain quote characters. These quotes can clash with the auto-generated SQL and result in syntax errors. In these cases a SelectArg is required. If you are passing in arguments from any user-input, you can use SelectArg to protect yourself from these so called SQL injection security problems. Lastly, certain data types use an internal SelectArg object because the string value of the object does not reliably match the database form of the object – java.util.Date is one example of such a type.

NOTE: SelectArg objects have protection against being used in more than one column name. You must instantiate a new object if you want to use a SelectArg with another column.

3.7 Using Column Arguments

Typically when you use the QueryBuilder you ae comparing a column and a value. To compare one column against another you can use a ColumnArg.

For example:

QueryBuilder<Account, String> queryBuilder =
  accountDao.queryBuilder();
// list all of the accounts that have the same
// name and password field 
queryBuilder.where().eq(Account.NAME_FIELD_NAME,
    new ColumnArg(Account.PASSWORD_FIELD_NAME));
List<Account> results = queryBuilder.query();

The ColumnArg can also take a table-name which is useful with JOIN queries to compare a column from one table with one in another table. See section Building Join Queries.

For example:

QueryBuilder<Order, Integer> orderQb = orderDao.queryBuilder();
orderQb.where().ge("amount", 100.0F);
QueryBuilder<Account, Integer> accountQb = accountDao.queryBuilder();
// find all accounts who have an order larger than their limit
accountQb.where().gt(Account.MAX_LIMIT_AMOUNT_FIELD,
     new ColumnArg("orders", Order.AMOUNT_FIELD));
// join with the order query
List<Account> results = accountQb.join(orderQb).query();

3.8 Building Join Queries

ORMLite supports basic JOIN SQL queries. For more information about how JOIN queries work see JOIN documentation.

You setup a join query by building 2 QueryBuilder objects – one in the DAO from which you are returning objects, and another DAO which is related to the first. One of the objects must be a foreign field of the other object (either direction is supported) or the join methods will throw an exception.

For example, let’s say you want to return a set of Account objects what have an Order that is larger than $100. We would set it up something like the following:

QueryBuilder<Order, Integer> orderQb = orderDao.queryBuilder();
orderQb.where().ge("amount", 100.0F);
QueryBuilder<Account, Integer> accountQb = accountDao.queryBuilder();
// join with the order query
List<Account> results = accountQb.join(orderQb).query();

This will return all of the Account records that have a corresponding Order that has a value field that is more than 100.0. Notice that none of the Order information is returned by the query – just Account information is retrieved. You could also reverse the situation and, for example, return all of the orders that have an account whose first-name is equal to "Bob". To compare fields from different tables, you can use the ColumnArg class. See section Using Column Arguments.

ORMlite also supports the concept of "LEFT JOIN" which means, in the context of the above example, that accounts that have no orders will also be returned. Typically with a "normal" join, only accounts that have orders are candidates to be returned by the query. ORMLite does not support "RIGHT JOIN" or "FULL JOIN" since none of the "right" object’s information is being returned by the query.

Please note that other ORM libraries use JOIN statements to retrieve results from multiple tables to fill in foreign fields and foreign collections. ORMLite does not support this feature. You can only get results from one table using it.

4. Using With Android

4.1 Android Basics

Because of the lack of official support for JDBC in Android OS, ORMLite makes direct calls to the Android database APIs to access SQLite databases. You should make sure that you have downloaded and are depending on the ormlite-android.jar files, but not the ormlite-jdbc.jar version. Although a number of developers are using the package in their projects, we continue to improve how ORMLite integrates with the Android classes. Feedback on this would be welcome.

After you have read the getting started section (see section Getting Started), the following instructions should be followed to help you get ORMLite working under Android OS.

1. You will need to create your own database helper class which should extend the OrmLiteSqliteOpenHelper class. This class creates and upgrades the database when your application is installed and can also provide the DAO classes used by your other classes. Your helper class must implement the methods onCreate(SQLiteDatabase sqliteDatabase, ConnectionSource connectionSource) and onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion). onCreate creates the database when your app is first installed while onUpgrade handles the upgrading of the database tables when you upgrade your app to a new version. There is a sample DatabaseHelper class as well as example projects online.
2. The helper can be kept open across all activities in your app with the same SQLite database connection reused by all threads. If you open multiple connections to the same database, stale data and unexpected results may occur. We recommend using the OpenHelperManager to monitor the usage of the helper – it will create it on the first access, track each time a part of your code is using it, and then it will close the last time the helper is released.
3. Once you have defined your database helper and are managing it correctly, you will need to use it in your Activity classes. An easy way to use the OpenHelperManager is to extend OrmLiteBaseActivity for each of your activity classes – there is also OrmLiteBaseListActivity, OrmLiteBaseService, and OrmLiteBaseTabActivity. These classes provide a helper protected field and a getHelper() method to access the database helper whenever it is needed and will automatically create the helper in the onCreate() method and release it in the onDestroy() method. See the sample HelloAndroid activity class in the examples. See section Android Examples.
4. If you do not want to extend the OrmLiteBaseActivity and other base classes then you will need to duplicate their functionality. You will need to call OpenHelperManager.getHelper(Context context, Class openHelperClass) at the start of your code, save the helper and use it as much as you want, and then call OpenHelperManager.release() when you are done with it. You will probably want to have something like the following in your classes:

   private DatabaseHelper databaseHelper = null; @Override protected void onDestroy() { super.onDestroy(); if (databaseHelper != null) { OpenHelperManager.releaseHelper(); databaseHelper = null; } } private DBHelper getHelper() { if (databaseHelper == null) { databaseHelper = OpenHelperManager.getHelper(this, DatabaseHelper.class); } return databaseHelper; }

5. By default, if you are using OrmLiteBaseActivity or other base classes, the OpenHelperManager will detect the database helper class through reflection. Another way to wire in the appropriate database helper class is to set the full class name of it in the the open_helper_classname value defined in the res/values/strings.xml resource file . You can also set the class using the OpenHelperManager.setOpenHelperClass(Class) method in a static {} block in your code.
6. The Android native SQLite database type is SqliteAndroidDatabaseType and is used by the base classes internally.
7. WARNING: You must make sure that any background threads call the OpenHelperManager.getHelper() and release() methods appropriately. Otherwise, if they access the database before it is opened or after it is closed, you will get exceptions.

Please see the example code documentation for more information. See section Android Examples. Again, feedback on this is welcome.

4.2 Using Table Config File

For some time we have been struggling with DAO startup issues under Android that we thought were due to ORMLite object bandwidth. Although improvements and DAO caching has been made, creating a couple of DAOs when your application starts can still take too long and generate far too much garbage collection activity. Turns out that one of the major culprits is some ugly code down in the Android OS – especially in Method.equals(). Because annotations use this method, looking up annotation values is extremely expensive, often garbage collecting thousands of objects and megabytes of space. Android knows about the issues and a fix has been made but we have no idea when these performance improvements will make it into an Android release.

With a little bit of work (and some caveats), you can remove all annotation work from your application and make DAO creation an extremely fast operation. ORMLite supports the loading of the data configurations from a text configuration file. When a DAO is created, these configurations will be used, removing the need for any annotation method calls entirely.

1. The OrmLiteConfigUtil utility class writes a ormlite_config.txt configuration file in the raw resource folder res/raw/ormlite_config.txt. You will need to extend this class into your own project along side your DatabaseHelper class. It should look something like:

   public class DatabaseConfigUtil extends OrmLiteConfigUtil { public static void main(String[] args) throws Exception { writeConfigFile("ormlite_config.txt"); } }

2. You will need to run this utility locally on your development box (not in an Android device), whenever you make a change to one of your data classes. This means that right now, this must be done by hand to keep the configuration file in sync with your database classes. To run the utility you will need to use the local Java runtime environment (JRE). Under eclipse, edit the "Run Configuration" for the utility, select the JRE tab, and select an alternative JRE (1.7 or above). Your project’s JRE should be undefined since it is an Android application. You’ll also need to remove the Android bootstrap entry from the Classpath tab.
3. By default this utility will look in the current directory and below in files ending in .java for the existence of one of the @DatabaseTable or DatabaseField annotations. These classes will be investigated and written into the database configuration file. You can also list the classes to be processed:

   public class DatabaseConfigUtil extends OrmLiteConfigUtil { private static final Class<?>[] classes = new Class[] { SimpleData.class, }; public static void main(String[] args) throws Exception { writeConfigFile("ormlite_config.txt", classes); } }

4. When the utility is run it should create the ormlite_config.txt configuration file in the raw resource folder. This folder must exist before the utility is run. Afterwards, if you refresh your project your should see the file appear. In the Eclipse console, you should see something like the following outputted by the utility:

   Writing configurations to /HelloAndroid/./res/raw/ormlite_config.txt Wrote config for class com.example.helloandroid.SimpleData Done.

   The config file generated should look something like:

   # # generated on 2020/09/15 01:42:02 # # --table-start-- dataClass=com.example.helloandroid.SimpleData tableName=simpledata # --table-fields-start-- # --field-start-- fieldName=id canBeNull=true generatedId=true …

5. The first time you create the config file in the resource folder, the Android build plugin should add it to the R.java file inside of the gen folder. This defines a unique integer value so that the application can open this resource by file-id number. The file should contain something like:

   public final class R { … public static final class raw { public static final int ormlite_config=0x7f040000; } … }

6. After the R.java file entry has been generated, you will need to enable the reading of the file at runtime. Inside of your DatabaseHelper class, you will need to change the constructor to add the integer file-id. The constructor will look something like the following:

   public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION, R.raw.ormlite_config); }

   Notice the R.raw.ormlite_config entry at the end that passes the file-id to the super class so it can be read in. You can also pass in a file-name or a Java File if you want to load in the config file from another location.

7. When you build and run your application, you will know that the database configuration file is being loaded if you see log entries like the following:

   I/DaoManager( 999): Loaded configuration for class ...SimpleData

   Oh, and if it is working you should notice a significant lack of GC messages during DAO startup.

As of 9/2011, this is one of the newest parts of ORMLite so we most likely will be improving it. Feedback is welcome.

4.3 Android Logging

The ormlite-android.jar classes define the AndroidLog class which is the Android specific version of ORMLite logging. This class makes calls to the Log.d, Log.i, … methods in the Android API. To see the log output, you will need to use the adb utility to view the log output:

adb logcat

Since INFO is the default under Android, only message such as the following will be spit out by default:

I/TableUtils(  254): creating table 'simpledata'
I/TableUtils(  254): creating index 'simpledata_string_idx' for table
   'simpledata
I/TableUtils(  254): executed create table statement changed 1 rows:
   CREATE TABLE `simpledata` (`date` VARCHAR, `id` INTEGER PRIMARY
   KEY AUTOINCREMENT , `even` SMALLINT )
I/TableUtils(  254): executed create table statement changed 1 rows:
   CREATE INDEX `simpledata_string_idx` ON `simpledata` ( `string` )

To enable more debug information you will want to do something like the following to turn on logging for a particular class:

adb shell setprop log.tag.StatementExecutor VERBOSE
adb shell setprop log.tag.BaseMappedStatement VERBOSE
adb shell setprop log.tag.MappedCreate VERBOSE

This enables messages such as:

D/BaseMappedStatement(465): create object using 'INSERT INTO `simpledata`
   (`date` ,`string` ,`millis` ,`even` ) VALUES (?,?,?,?)' and 4 args,
   changed 1 rows
D/BaseMappedStatement(465): assigned id '9' from keyholder to 'id' in
   SimpleData object

To enable all debug messages for all ORMLite classes then use the following:

adb shell setprop log.tag.ORMLite DEBUG

NOTE: Unfortunately, Android property names are limited in size so the ORMLite logger only takes that last 23 [sic] characters of the class name if it is larger than 23 characters. For example, if the class is AndroidDatabaseConnection you would do:

adb shell setprop log.tag.droidDatabaseConnection VERBOSE

If you are trying to track operations performed to the database by ORMLite use:

adb shell setprop log.tag.droidDatabaseConnection VERBOSE
adb shell setprop log.tag.ndroidCompiledStatement VERBOSE

Proguard can cause the internal logging code to get confused and not log things to the Android log. You will need to add the following lien to your proguard.cfg to work around this:

-keep class com.j256.ormlite.android.AndroidLog { *; }

To force the logging backend to use Android logging, you should call the following method as early as possible in your application.

LoggerFactory.setLogBackendFactory(LogBackendType.ANDROID);

To disable all logs, you can use the following code also called as early as possible:

LoggerFactory.setLogBackendFactory(LogBackendType.NULL);.

4.4 Runtime Versus SQL Exceptions

By default, most of the DAO methods throw SQLException which is the default internal exception for most JDBC and other SQL calls. But in Android-land, especially, most of the exceptions extend RuntimeException so having to put a lot of ignored try ... catch stanzas is inconvenient. For this reason we’ve added a RuntimeExceptionDao which wraps all calls to the underlying DAO to rethrow the SQL exceptions as runtime exceptions. To get one, you can wrap your own down in it:

Dao<Account, String> dao =
  DaoManager.createDao(connectionSource, Account.class);
RuntimeExceptionDao<Account, String> accountDao =
  new RuntimeExceptionDao<Account, String>(dao);

Or you can call the createDao helper methods on RuntimeExceptionDao:

RuntimeExceptionDao<Account, String> accountDao =
  RuntimeExceptionDao.createDao(connectionSource, Account.class);

Other classes such as TableUtils and QueryBuilder still throw SQLException but the hope is that RuntimeExceptionDao helps a little bit at least.

4.5 Upgrading Your Schema

When you upgrade your application, you may have to add columns or make other changes to the data that was stored by previous versions of your application. If you are on Android then in your DatabaseHelper, there should be an onUpgrade() method that extends the following method from the OrmLiteSqliteOpenHelper.

abstract void onUpgrade(SQLiteDatabase database,
  ConnectionSource connectionSource, int oldVersion, int newVersion)

In that method you can use your DAO to perform any tweaks to the schema:

Dao<Account, Integer> dao = getHelper().getAccountDao();
// change the table to add a new column named "age" 
dao.executeRaw("ALTER TABLE `account` ADD COLUMN age INTEGER;");

Here’s more information about SQLite’s ALTER TABLE. In SQLite, all you can do is rename a table name and add a new column. You can’t rename or remove a column or change the constraints. Remember that SQLite is typeless so changing the type of a column doesn’t matter.

Most likely, you should make your schema changes conditional to the version you are upgrading from:

if (oldVersion < 2) {
  // we added the age column in version 2
  dao.executeRaw("ALTER TABLE `account` ADD COLUMN age INTEGER;");
}
if (oldVersion < 3) {
  // we added the weight column in version 3
  dao.executeRaw("ALTER TABLE `account` ADD COLUMN weight INTEGER;");
}

You can also modify data in the tables using something like the following:

dao.executeRaw(
    "ALTER TABLE `account` ADD COLUMN hasDog BOOLEAN DEFAULT 0;");
dao.updateRaw("UPDATE `account` SET hasDog = 1 WHERE dogCount > 0;");

If you are using some other database over JDBC then the above commands will work but you will have to handle the versioning of your application manually.

5. Advanced Concepts

5.1 Spring Configuration

ORMLite contains some classes which make it easy to configure the various database classes using the Spring Framework.

TableCreator

Spring bean that auto-creates any tables that it finds DAOs for if the system property ormlite.auto.create.tables has been set to true. It will also auto-drop any tables that were auto-created if the property ormlite.auto.drop.tables has been set to true. This should be used carefully and probably only in tests.

DaoFactory

Spring bean that can be used to create Dao’s for certain classes without needing to define their own Dao class.

Here’s an example of a full Spring configuration.

<!-- URL used for database, probably should be in properties file -->
<bean id="databaseUrl" class="java.lang.String">
    <!-- we are using the in-memory H2 database in this example -->
    <constructor-arg index="0" value="jdbc:h2:mem:account" />
</bean>

<!-- datasource used by ORMLite to connect to the database -->
<bean id="connectionSource"
    class="com.j256.ormlite.jdbc.JdbcConnectionSource"
    init-method="initialize">
    <property name="url" ref="databaseUrl" />
    <!-- probably should use system properties for these too -->
    <property name="username" value="foo" />
    <property name="password" value="bar" />
</bean>

<!-- abstract dao that is common to all defined daos -->
<bean id="baseDao" abstract="true" init-method="initialize">
    <property name="connectionSource" ref="connectionSource" />
</bean>

<!-- our daos -->
<bean id="accountDao"
    class="com.j256.ormlite.examples.common.AccountDaoImpl"
    parent="baseDao" />
<bean id="deliveryDao" class="com.j256.ormlite.spring.DaoFactory"
  factory-method="createDao">
    <constructor-arg index="0" ref="connectionSource" />
    <constructor-arg index="1"
      value="com.j256.ormlite.examples.spring.Delivery" />
</bean>

You can also take a look at the spring example code. See spring example.

5.2 Class Configuration

The simplest mechanism for configuring a class to be persisted by ORMLite is to use the @DatabaseTable and @DatabaseField annotations. See section Adding ORMLite Annotations. However if you do not own the class you are persisting or there are permission problems with the class, you may want to configure the class using Java code instead.

To configure a class in code, you use the DatabaseFieldConfig and DatabaseTableConfig objects. The field config object holds all of the details that are in the @DatabaseField annotation as well as the name of the corresponding field in the object. The DatabaseTableConfig object holds the class and the corresponding list of DatabaseFieldConfigs. For example, to configure the Account object using Java code you’d do something like the following:

List<DatabaseFieldConfig> fieldConfigs =
    new ArrayList<DatabaseFieldConfig>();
DatabaseFieldConfig field1 = new DatabaseFieldConfig("name");
field1.setId(true);
fieldConfigs.add(field1);
DatabaseFieldConfig field2 = new DatabaseFieldConfig("password");
field2.setCanBeNull(false);
fieldConfigs.add(field2);
DatabaseTableConfig<Account> accountTableConfig
    = new DatabaseTableConfig<Account>(Account.class, fieldConfigs);

AccountDaoImpl accountDao =
    new AccountDaoImpl(connectionSource, accountTableConfig);

See the Javadocs for the DatabaseFieldConfig class for the fields to pass to the constructor. You can also use the no-argument constructor and call the setters for each field. You use the setters as well when you are configuring a class using Spring wiring. Here is the above example in Spring:

<bean id="accountTableConfig"
  class="com.j256.ormlite.table.DatabaseTableConfig">
    <property name="dataClass"
        value="com.j256.ormlite.examples.common.Account" />
    <property name="tableName" value="account" />
    <property name="fieldConfigs">
        <list>
            <bean class="com.j256.ormlite.field.DatabaseFieldConfig">
                <property name="fieldName" value="name" />
                <property name="id" value="true" />
            </bean>
            <bean class="com.j256.ormlite.field.DatabaseFieldConfig">
                <property name="fieldName" value="password" />
                <property name="canBeNull" value="false" />
            </bean>
        </list>
    </property>
</bean>

You can also look at the field configuration example code. See field config example.

5.3 Database Specific Code

ORMLite uses an internal DatabaseType object which defines all of the per-database information necessary to support the various features on all of the different database types. The JdbcConnectionSource uses the database URL to pick the correct DatabaseType. If it picks an incorrect one then you may need to set the DatabaseType on the connection source directly. For example:

String databaseUrl = "jdbc:derby://dbserver1:1527/";
DatabaseType databaseType = new DerbyClientServerDatabaseType();
ConnectionSource connectionSource =
   new JdbcConnectionSource(databaseUrl, databaseType);

Android users do not need to worry about this because the AndroidConnectionSource always uses the SqliteAndroidDatabaseType. See section Using With Android.

The DatabaseType classes are found in com.j256.ormlite.db. Each of the supported databases has a class there which implements the code needed to handle the unique features of the database (H2DatabaseType, MySqlDatabaseType, etc.). If you want to help develop and test against other SQL databases, a externally available server that the author could connect to and test against would be appreciated. Please contact the author if your database is not supported or if you want to help.

The following methods are currently used by the system to isolate the database specific behavior in one place. See the javadocs for the DatabaseType class for the most up to date information.

isDatabaseUrlThisType

Return true if the database URL corresponds to this database type. Usually the URL is in the form jdbc:ddd:… where ddd is the driver url part.

loadDriver

Load the driver class associated with this database so it can wire itself into JDBC.

appendColumnArg

Takes a field type and appends the SQL necessary to create the field. It may also generate arguments for the end of the table create statement or commands that must run before or after the table create.

dropColumnArg

Takes a field type and adds all of the commands necessary to drop the column from the database.

appendEscapedEntityName

Add a entity-name (table or column name) word to the SQL wrapped in the proper characters to escape it. This avoids problems with table, column, and sequence-names being reserved words.

appendEscapedWord

Add the word to the string builder wrapped in the proper characters to escape it. This avoids problems with data values being reserved words.

generateIdSequenceName

Return the name of an ID sequence based on the table-name and the field-type of the id. This is required by some database types when we have generated ids.

getCommentLinePrefix

Return the prefix to put at the front of a SQL line to mark it as a comment.

isIdSequenceNeeded

Return true if the database needs a sequence when you insert for generated IDs. Some databases handle generated ids internally.

getFieldConverter

Return the field converter associated with a particular field type. This allows the database instance to convert a field as necessary before it goes to the database.

isVarcharFieldWidthSupported

Return true if the database supports the width parameter on VARCHAR fields.

isLimitSqlSupported

Return true if the database supports the LIMIT sql command.

isLimitAfterSelect

Return true if the LIMIT should be called after SELECT otherwise at the end of the WHERE (the default).

appendLimitValue

Add the necessary SQL to limit the results to a certain number.

isOffsetSqlSupported

Return true if the database supports the OFFSET SQL command in some form.

isOffsetLimitArgument

Return true if the database supports the offset as a comma argument from the limit. This also means that the limit must be specified if the offset is specified.

appendOffsetValue

Append to the string builder the necessary SQL to start the results at a certain row number.

appendSelectNextValFromSequence

Add the SQL necessary to get the next-value from a sequence. This is only necessary if isIdSequenceNeeded returns true.

appendCreateTableSuffix

Append the SQL necessary to properly finish a CREATE TABLE line.

isCreateTableReturnsZero

Returns true if a ’CREATE TABLE’ statement should return 0. False if > 0.

isEntityNamesMustBeUpCase

Returns true if table and field names should be made uppercase. This is an unfortunate "feature" of Derby and Hsqldb. See the Javadocs for the class for more information.

isNestedSavePointsSupported

Returns true if the database supports nested savepoints (transactions).

getPingStatement

Return an statement that doesn’t do anything but which can be used to ping the database by sending it over a database connection.

isBatchUseTransaction

Returns true if batch operations should be done inside of a transaction. Default is false in which case auto-commit disabling will be done.

isTruncateSupported

Returns true if the table truncate operation is supported.

isCreateIfNotExistsSupported

Returns true if the table creation IF NOT EXISTS syntax is supported.

5.4 DAO Methods

The DAO classes provide the following methods that you can use to store your objects to your database. This list may be out of date. See the Dao interface class for the latest methods.

queryForId(ID id)

Looks up the id in the database and retrieves an object associated with it.

queryForFirst(PreparedQuery<T> preparedQuery)

Query for and return the first item in the object table which matches a prepared statement. This can be used to return the object that matches a single unique column. You should use queryForId if you want to query for the id column.

queryForAll()

Query for all of the items in the object table and return a list of them. For medium sized or large tables, this may load a lot of objects into memory so you should consider using the iterator method instead.

queryForEq(String fieldName, Object value)

Query for the items in the object table that match a simple where with a single field = value type of WHERE clause. This is a convenience method for calling queryBuilder().where().eq(fieldName, value).query().

queryForMatching(T matchObj)

Query for the rows in the database that match the object passed in as an argument. Any fields in the matching object that are not the default value (null, false, 0, 0.0, etc.) are used as the matching parameters with AND. If you are worried about SQL quote escaping, you should use queryForMatchingArgs.

queryForMatchingArgs(T matchObj)

Same as queryForMatching but this uses SQL ? arguments. This is slightly more expensive but you don’t have to worry about SQL quote escaping.

queryForFieldValues(Map<String, Object> fieldValues)

Query for the rows in the database that matches all of the field to value entries from the map passed in.

queryForFieldValuesArgs(Map<String, Object> fieldValues)

Same as queryForFieldValues but this uses SQL ? arguments. This is slightly more expensive but you don’t have to worry about SQL quote escaping.

queryForSameId(T data)

Query for a data item in the table that has the same ID as the data parameter.

queryBuilder()

Create and return a new QueryBuilder object which allows you to build a custom query. See section Query Builder Basics.

updateBuilder()

Create and return a new UpdateBuilder object which allows you to build a custom update statement. See UpdateBuilder.

deleteBuilder()

Create and return a new DeleteBuilder object which allows you to build a custom delete statement. See DeleteBuilder.

query(PreparedQuery<T> preparedQuery)

Query for the items in the object table which match a prepared statement. See section Custom Statement Builder. This returns a list of matching objects. For medium sized or large tables, this may load a lot of objects into memory so you should consider using the iterator method instead.

create(T data)

Create a new entry in the database from an object. Should return 1 indicating 1 row was inserted.

createIfNotExists(T data)

This is a convenience method to creating a data item but only if the ID does not already exist in the table. This extracts the id from the data parameter, does a query for on it, returning the data if it exists. If it does not exist then create is called with the data parameter.

createOrUpdate(T data)

This is a convenience method for creating an item in the database if it does not exist. The id is extracted from the data argument and a query-by-id is made on the database. If a row in the database with the same id exists then all of the columns in the database will be updated from the fields in the data parameter. If the id is null (or 0 or some other default value) or doesn’t exist in the database then the object will be created in the database. This also means that your data item must have an id field defined.

update(T data)

Save the fields from an object to the database. If you have made changes to an object, this is how you persist those changes to the database. You cannot use this method to update the id field – see updateId(). This should return 1 since 1 row was updated.

updateId(T data, ID newId)

Update an object in the database to change its id to a new id. The data must have its current id set and the new-id is passed in as an argument. After the id has been updated in the database, the id field of the data object will also be changed. This should return 1 since 1 row was updated.

update(PreparedUpdate<T> preparedUpdate)

Update objects that match a custom update statement.

refresh(T data, ID newId)

Does a query for the object’s id and copies in each of the field values from the database to refresh the data parameter. Any local object changes to persisted fields will be overwritten. If the database has been updated this brings your local object up-to-date. This should return 1 since 1 row was retrieved.

delete(T data)

Delete an object from the database. This should return 1 since 1 row was removed.

deleteById(ID id)

Delete an object from the database if you have its id. This should return 1 since 1 row was removed.

delete(Collection<T> datas)

Delete a collection of objects from the database using an IN SQL clause. This returns the number of rows that were deleted.

deleteIds(Collection<ID> ids)

Delete the objects that match the collection of ids from the database using an IN SQL clause. This returns the number of rows that were deleted.

delete(PreparedDelete<T> preparedDelete)

Delete objects that match a custom delete statement.

iterator()

This method satisfies the Iterable Java interface for the class and allows you to iterate through the objects in the table using SQL. This method allows you to do something like:

for (Account account : accountDao) { … }

WARNING: See the Dao class for warnings about using this method.

iterator(PreparedQuery<T> preparedQuery)

Same is the iterator method but with a prepared statement parameter. See section Custom Statement Builder.

getWrappedIterable()

This returns a one time use iterable class that can be closed afterwards. The DAO itself is CloseableWrappedIterable but multiple threads can each call this to get their own closeable iterable. This allows you to do something like:

CloseableWrappedIterable<Account> wrappedIterable = accountDao.getWrappedIterable(); try { for (Account account : wrappedIterable) { … } } finally { wrappedIterable.close(); }

getWrappedIterable(PreparedQuery<T> preparedQuery)

Same as getWrappedIterable() but with a prepared query parameter.

closeLastIterator()

This closes the last iterator returned by the iterator() method.

NOTE: This is not reentrant. If multiple threads are getting iterators from this DAO then you should use getWrappedIterable() method.

queryRaw(String query, String... arguments)

Query for all of the items in the object table that match the SQL select query argument. This method allows you to do special queries that aren’t supported otherwise. For medium sized or large tables, this may load a lot of objects into memory so you should consider using the iterator() method on the GenericRawResults instead of the getResults method. See section Issuing Raw Queries.

queryRaw(String query, RawRowMapper<UO> mapper, String... arguments)

Same as the above queryRaw method but with the addition of a row mapper. Instead of each row being returned as an array of strings, this will map the row using the mapper object passed in. See section Issuing Raw Queries.

queryRaw(String query, DataType[] columnTypes, RawRowObjectMapper<UO> mapper, String... arguments)

Similar to the above queryRaw but uses the column-types array to present an array of object results to the mapper instead of strings. The arguments are optional but can be set with strings to expand ? type of SQL. See section Issuing Raw Queries.

queryRaw(String query, DataType[] columnTypes)

Same as the above queryRaw method but with the addition of a an array of column data types. Instead of each row being returned as an array of strings, they are returned as an array of objects. See section Issuing Raw Queries.

queryRawValue(String query, String... arguments)

Perform a raw query that returns a single value (usually an aggregate function like MAX or COUNT). If the query does not return a single long value then it will throw a SQLException.

executeRaw(String statement)

Run a raw execute SQL statement against the database. See section Issuing Raw Execute Statements.

updateRaw(String statement)

Run a raw update SQL statement (INSERT, DELETE, or UPDATE against the database. See section Issuing Raw Update Statements.

callBatchTasks(Callable callable)

Call the call-able that will perform a number of batch tasks. This is for performance when you want to run a number of database operations at once – maybe loading data from a file. This will turn off what databases call "auto-commit" mode, run the call-able and then re-enable "auto-commit". If auto-commit is not supported then it will try to use a database transaction to speed up the tasks.

NOTE: If neither auto-commit nor transactions are supported by the database type then this method may not give any performance improvement.

accountDao.callBatchTasks(new Callable<Void>() { public Void call() throws SQLException { // insert a number of accounts at once for (Account account : accountsToInsert) { // update our account object accountDao.create(account); } return null; } });

countOf()

Returns the value returned from a SELECT COUNT(*) query which is the number of rows in the table. Depending on the database and the size of the table, this could be expensive.

countOf(PreparedQuery<T> preparedQuery)

Returns the number of rows in the table associated with the prepared query passed in. Depending on the size of the table and the database type, this may be expensive and take a while.

assignEmptyForeignCollection(T parent, String fieldName)

Assigns an empty collection to the appropriate collection field that has the field-name. This allows you to add things to the collection from the start. This allows you to do something like:

accoundDao.assignEmptyForeignCollection(account, "orders"); // this would add it the collection and the internal DAO account.orders.add(order1);

setObjectCache(boolean enabled);

Call this with true to enable an object cache for the DAO. Set to false to disable any caching. See section Object Caches.

setObjectCache(ObjectCache objectCache);

Same as setObjectCache(boolean) except you specify the actual cache instance to use for the DAO. This allows you to inject your own cache classes. Call it with null to disable the cache. See section Object Caches.

clearObjectCache();

Flush the object cache if it has been enabled. This will remove an objects that are in the cache to reclaim memory. Any future queries will re-request them from the database.

mapSelectStarRow(DatabaseResults results)

Return the latest row from the database results from a query to select * (star). This allows you to remap the results. It is particularly useful if you are repositioning a database cursor externally.

getSelectStarRowMapper()

Return a row mapper that is suitable for mapping results from a query to select * (star).

idExists(ID id)

Returns true if an object exists that matches this ID otherwise false.

startThreadConnection()

WARNING: This method is for advanced users only. It is only to support the setAutoCommit(conn, boolean) and other methods below. Chances are you should be using the TransactionManager class’ callInTransaction(Callable) method instead f this method unless you know what you are doing.

This allocates a connection for this specific thread that will be used in all other DAO operations. The thread must call endThreadConnection(conn) once it is done with the connection. It is highly recommended that a try / finally pattern be used here to ensure you do not leak connections.

This is really only useful if you are using a pooled connection source and want to do certain operations on the same pool. Android users, for example have a single connection to the database so this is effectively a no-op.

endThreadConnection(DatabaseConnection connection)

This method is used to free the connection returned by the startThreadConnection() above.

setAutoCommit(DatabaseConnection connection, boolean autoCommit)

Set auto-commit mode to be true or false on the connection returned by the startThreadConnection(). This may not be supported by all database types.

isAutoCommit(DatabaseConnection connection)

Return true if the database connection returned by the startThreadConnection() is in auto-commit mode otherwise false. This may not be supported by all database types.

commit(DatabaseConnection connection)

If you have previously called setAutoCommit(conn, false) then this will commit all changes to the database made from that point up to now on the connection returned by the startThreadConnection(). The changes will be written to the database and discarded. The connection will continue to stay in the current auto-commit mode.

WARNING: Chances are you should be using the TransactionManager class’ callInTransaction(Callable) method instead unless you know what you are doing.

rollBack(DatabaseConnection connection)

If you have previously called setAutoCommit(conn, false) then this will roll-back and flush all changes to the database made from that point up to now on the connection returned by the startThreadConnection(). None of those changes will be written to the database and are discarded. The connection will continue to stay in the current auto-commit mode.

WARNING: Chances are you should be using the TransactionManager class’ callInTransaction(Callable) method instead unless you know what you are doing.

5.5 ORMLite Logging

ORMLite uses a log system which can plug into Apache commons logging, Log4j, Android Log, or its own internal log implementations. The logger code first looks for the android.util.Log and if found will use the Android internal logger. Next it looks for org.apache.commons.logging.LogFactory class in the class-path – if found it will use Apache commons logging. If that class is not found it then looks for org.apache.log4j.Logger and if found will use Log4j. If none of these classes are available it will use an internal logger – see LocalLog. The logger code also provides simple {} argument expansion like slf4j which means that you can save on toString() calls and StringBuilder operations if the log level is not high enough. This allows us to do something like the following:

private static Logger logger =
  LoggerFactory.getLogger(QueryBuilder.class);
…
logger.debug("built statement {}", statement);

If you are using log4j (through Apache commons logging or directly), you can use something like the following as your log4j.properties file to see details about the SQL calls.

log4j.rootLogger=INFO, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# print the date in ISO 8601 format
log4j.appender.stdout.layout.ConversionPattern=%d{ISO8601} [%p] %c{1} %m%n

# be more verbose with our code
log4j.logger.com.j256.ormlite=DEBUG

# to enable logging of arguments to all of the SQL calls
# uncomment the following lines
#log4j.logger.com.j256.ormlite.stmt.mapped.BaseMappedStatement=TRACE
#log4j.logger.com.j256.ormlite.stmt.mapped.MappedCreate=TRACE
#log4j.logger.com.j256.ormlite.stmt.StatementExecutor=TRACE

Notice that you can uncomment the last lines in the above log4j.properties file to log the arguments to the various SQL calls. This may expose passwords or other sensitive information in the database so probably should only be used during debugging and should not be the default.

If you are using the LocalLog logger (which is helpful for testing at least) then you can configure it using a ormliteLocalLog.properties file. The file configures the log output of the ORMLite LocalLog class. Lines in the file have the format class-regex-pattern = Level. For example:

com\.j256\.ormlite.* = DEBUG
com\.j256\.ormlite\.stmt\.mapped\.BaseMappedStatement = TRACE
com\.j256\.ormlite\.stmt\.mapped\.MappedCreate = TRACE
com\.j256\.ormlite\.stmt\.StatementExecutor = TRACE

NOTE: You should escape any period characters with a single backslash unless they are part of a regex match.

For all of the logging implementations, you can use the Logger.setGlobalLogLevel(...) method to filter all log messages. The argument you pass in filters out any messages to less important levels. You should call that method in the main(...) method or as early in your application as possible.

// filter out TRACE messages only
Logger.setGlobalLogLevel(Level.DEBUG);
// only allow error or fatal messages
Logger.setGlobalLogLevel(Level.ERROR);
// turn off all log messages
Logger.setGlobalLogLevel(Level.OFF);

You can also implement your own logging implementation by using the LoggerFactory.setLogFactory(...) method. The the factory needs to implement a Log createLog(String) method and the Log class only has a couple methods to test the log level and log messages with optional throwables.

To force the logging backend to use a particular logging system, you should call the following method as early as possible in your application.

LoggerFactory.setLogBackendFactory(LogBackendType.SLF4J);

You can use the NullLogFactory as another way to disable all log messages by sending them to NullLog which ignores all log calls.

To disable all logs, you can use the following code also called as early as possible which ignores all log messages.

LoggerFactory.setLogBackendFactory(LogBackendType.NULL);.

For logging with Android, See section Android Logging.

5.6 External Dependencies

ORMLite does not have any direct dependencies. It has logging classes that depend on Apache commons-logging and Log4j but these classes will not be referenced unless they exist in the class-path.

If you want to get the ORMLite Junit tests to run, there are test dependencies on the following packages:

javax.persistence

For testing the compatibility annotations @Column and the like.

org.junit

We use Junit for our unit tasks.

org.easymock.easymock

We use, and are in love with, EasyMock. It allows us to mock out dependencies so we can concentrate on testing a particular class instead of the whole package.

com.h2database

As a test database implementation, H2 is very fast and simple to use. However, we recommend MySQL or Postgres for multi-threaded, high-performance, production databases.

5.7 Using Database Transactions

Database transactions allow you to make a number of changes to the database and then if any of them fail, none of the changes are actually written. For example, let’s say you are recording an order into your order entry system which requires you to insert a row into the Order table and also to update the Account table with the order number. If the Order was inserted but then a disk error stopped the Account from being updated, the Order data would be left dangling. If you used a transaction then both changes would be saved to the database only when the transaction was closed. Most (not all) databases support transactions which are designed specifically with these sorts of scenarios in mind.

ORMLite has basic support for transactions through the use of the TransactionManager class which wraps databases operations in a transaction. If those operations throw an exception, then the transaction is "rolled-back" and none of the operations are persisted to the database. Once the operations are finished, if no exception is thrown, then the transaction is "committed" and the changes are written to the database.

// we need the final to see it within the Callable
final Order order = new Order();

TransactionManager.callInTransaction(connectionSource,
  new Callable<Void>() {
    public Void call() throws Exception {
        // insert our order
        orderDao.create(order);
        // now add the order to the account
        account.setOrder(order);
        // update our account object
        accountDao.update(account);
        // you could pass back an object here
        return null;
    }
});

If for some reason, the accountDao.update() fails in the above example, the order insert will not be committed to the database. Transactions allow you to make multiple operations while still ensuring data integrity. Notice that you can return an object from the callable so you could pass back the number of rows affected or other information.

NOTE: Performing database operations within a transaction also has the side effect of better performance since a number of changes are written at once in a batch. The Dao.callBatchTasks() method should always be used if you are looking for performance of a large number of operations. See callBatchTasks.

5.8 Object Caches

ORMLite supports the ability to enable a basic object cache for a DAO. The object cache keeps an internal collection of objects that have been created or queried and will return a reference to the same object if it is handled in the future.

For example:

Dao<Account, String> accountDao =
    DaoManager.createDao(connectionSource, Account.class);
// enable the default object cache for this dao
accountDao.setObjectCache(true);

Account account = new Account("Jim Coakley");
accountDao.create(account);
// this will create the account object and add it to cache

Account result = dao.queryForId("Jim Coakley");
// this result will be the same object as account above
assertSame(account, result);

NOTE: For an object cache to work, the class being stored must have an ID field. If you try to enable the object cache for a class without an ID field, an exception will be thrown. The following operations are supported by the object cache:

• If you create an object using the DAO, it will be added to the cache.
• When you query for an object using the standard query methods from the DAO, if the object is in the cache it will be returned. If it is not in the cache then it will be added to the cache. This does not apply to the queryRaw(...) methods.
• If you update an object with the database using the DAO, if it exists in the cache it will be updated as well.
• If you refresh an object from the database using the DAO, if it exists in the cache it will be refreshed as well.
• If you delete the object using the DAO, the object will be deleted from the cache. All delete methods are supported.

By default the cache that is used internally by ORMLite if you enable the cache with true will be a "weak-reference" cache. This means that if no other code has a strong reference to the object, it will be removed from the cache during the next garbage collection cycle. ORMLite also has a "soft-reference" cache which will use more memory to hold objects if available and supported by your OS. You can enable it using:

Dao<Account, String> accountDao =
    DaoManager.createDao(connectionSource, Account.class);
// enable a soft-reference cache
accountDao.setObjectCache(
    ReferenceObjectCache.makeSoftCache());

The reference caches store a small object that refers to the cached object. These small objects only get cleaned up when the object is accessed. You should consider calling the cleanNullReferencesAll() method on your cache to remove these objects and free up their associated memory on occasion.

There is also a Least Recently Used (LRU) cache that will store a certain number of objects based on a capacity value. Each class gets the same capacity value so if the same cache is used in 5 different daos, then 500 objects will be held in the LruObjectCache if the capacity is 100.

Dao<Account, String> accountDao =
  DaoManager.createDao(connectionSource, Account.class);
// enable least-recently-used cache with max 100 items per class
accountDao.setObjectCache(new LruObjectCache(100));

You can also implement your own cache class that implements the ObjectCache interface.

All of the caches can be cleared if you want to free up memory and you can also disable the cache from the DAO if necessary.

// clear all Account items from the cache
accountDao.clearObjectCache();
…
// disable the cache
accountDao.setObjectCache(false);

5.9 Configuring a Maven Project

To use ORMLite in your project if you are using maven, then you should add the following configuration stanza to your pom.xml file. As mentioned below, you will also need to add some database driver as well to your dependency list. In this example we are using MySQL but any of the supported JDBC database drivers will do.

<project>
    …
    <dependencies>
        <dependency>
            <groupId>com.j256.ormlite</groupId>
            <artifactId>ormlite-jdbc</artifactId>
            <version>6.1</version>
        </dependency>
        <!-- You will need to add some sort of database driver too.
             In this example we've used MySQL. -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.10</version>
        </dependency>
    </dependencies>
</project>

NOTE: I do not have any details about how to configure Android projects with maven. If you are doing so then just replace the ormlite-jdbc artifact name with ormlite-android.

5.10 Running Batch Operations

Every so often you need to efficiently do a number of database updates at one time – bulk database inserts is a common pattern. ORMLite supports a callBatchTasks method on the Dao class which supports this behavior in most database types. For example:

final List<Account> accountsToInsert = new ArrayList<Account>();
…
accountDao.callBatchTasks(new Callable<Void>() {
    public Void call() throws Exception {
        for (Account account : accountsToInsert) {
            accountDao.create(account);
        }
    }
});

Databases by default commit changes after every SQL operation. This method disables this "auto-commit" bahavior so a number of changes can be made faster and then committed all at once. More specifically, the method turns "auto-commit", calls the Callable.call() method passed in as an argument, calls SQL commit to persist the changes when the call returns, and finally re-enabled auto-commit. Some databases do not support auto-commit so a transaction may be used to accomplish the same behavior.

NOTE: If neither auto-commit nor transactions are supported by the database type then callBatchTasks method may do nothing.

5.11 Custom Data Type Persisters

ORMLite has internal definitions for storing the basic primitive and other common data types. See section Persisted Data Types. Sometimes, however, you either want to store a new data type in your database or you want to change the way ORMLite stores values to the database for common types – this often happens when you are trying to work with an existing schema. You can change how types are stored in the database by defining a class which implements the DataPersister interface.

For example, you might have a Date field in an existing database that was not nullable but instead stored the date 0000-00-00 when there was no date. You want ORMLite to return null if the 0 date was retrieved from the database. To implement a custom data persister to handle the Date type in this manner would probably override the com.j256.ormlite.field.types.DateType class and tweak the result-to-sql-argument method as follows:

@Override
public Object resultToSqlArg(FieldType fieldType,
      DatabaseResults results, int columnPos)
      throws SQLException {
   Timestamp timestamp = results.getTimestamp(columnPos);
   if (TODO: somehow test fo 0000-00-00 here)
      return null;
   else
      return timestamp;
}

The data persister example has a MyDatePersister class which does just that. See data persister example. To use your persister class on a particular field in your objects, you would do something like this:

@DatabaseField(persisterClass = MyDatePersister.class)
Date birthDate;

ORMLite also allows you to define data persisters for atypical or custom data types that are not handled at all by the internal classes. When defining a data persister class from scratch, you could extend one of the other data type persisters or the BaseDataType class. You will need to define the following methods.

1. parseDefaultString – Converts a default string into a SQL argument suitable to be loaded into the database.
2. resultToSqlArg – Uses the DatabaseResults object to get the right SQL argument type out of the results.
3. sqlArgToJava – Converts the SQL argument to the associated Java class.

Look at the other data types in com.j256.ormlite.field.types for other examples. When you have defined your persister class, you can use it with the persisterClass construct above or you can register it with the DataPersisterManager.registerPersisters(...) method. This will then automatically call your persister whenever a field with the associated class is configured.

DataPersisterManager.registerDataPersisters(
   MyTypePersister.getSingleton());

You probably would not want to register the MyDatePersister above because you would not want to change the persistence behavior for all Date types.

6. Upgrade From Old Versions

We strive to maintain backwards compatibility and to provide deprecated versions of old classes and methods. However, sometimes when a new version is released, changes are made that require programmers to change their code and rarely the on-disk database formats.

6.1 Notes About Version 6.1

Because of the fervor around the #Log4Shell bug, I’ve bumped the log4j2 release to 2.17.0. For the record ORMLite uses the SimpleLogging shim between it and the logging backends that would only access log4j2 if someone else provided the dependency. Also log4j2 2.17.0 depends on Java 8 while we are still on Java 7 so the tests have been ignored.

6.2 Notes About Version 6.0

ORMLite has [finally] moved to a shaded unified jar. You no longer need to add ormlite-core to your classpath when you use ormlite-jdbc or ormlite-android.

ORMLite now requires Java 7 and no longer supports Java 6. This allows us to change to using the AutoCloseable interface added in Java 7 which means that a number of the different close methods now throw Exception instead of IOException to match AutoCloseable.close().

Since we are moving to 6.0, we’ve removed some of the @Deprecated methods that had been around for a while.

6.3 Notes About Version 5.7

Added some provisional Stream support to lazy foreign collections to help with the proper closing of the underlying iterator and marking of it as unsized. We were able to support this while still keeping Java 6 compilation level.

6.4 Notes About Version 5.2

In version 5.2, we fixed issues with the boolean SQL types. The boolean number type now correctly uses the BOOLEAN SQL type instead of BYTE. The boolean character type now correctly uses the CHAR SQL type instead of STRING. Although we don’t anticipate any issues with this, the developers thought it prudent to mention it in case it causes compatibility issues.

We also did refactoring in the ormlite-jdbc jar by renaming a number of types so it could be fulling Java9 compliant. Before there were overlapping packages. Now all code in the ormlite-jdbc is under the com.j256.ormlite.jdbc package. You may need to edit your imports if you were refering to any of these classes.

6.5 Notes About Version 5.1

In version 5.0, we moved to using English for the field and method name capitalization because of problems with how certain languages capitalize certain characters. Some of the capitalization points were missed however and this version fixes a couple of additional spots where field and method capitalization was still using the default locale.

If you want ORMLite to use the old way to keep compatibility, you should generate your connection source with a custom database type that uses your default locale by overriding the following methods:

• upCaseEntityName(String)
• upCaseString(String, boolean)
• downCaseString(String, boolean)

These methods should just return string.toUpper() or string.toLower() which will use your default locale. You can also specify a specific locale if necessary.

6.6 Notes About Version 5.0

A number of things have changed and it’s been a long time since the last published ORMLite release, so a .0 number on the release seemed to be warranted. See the following details.

• ORMLite now requires Java 6 and no longer supports Java 5.
• We used the native locale to do uppercase database entity names (tables and fields). This sounds like a good idea until you realize that in Turkish, a uppercase i with a dot is a capital I with a dot which can be incompatible with databases that don’t understand UTF8 names. For this reason the default behavior is to do capitalization of entities using Locale.ENGLISH. This means that your schema may need to change. To go back to the old behavior, you should override the appropriate DatabaseType and override the upCaseEntityName(String) method.
• We’ve added the usage of the java.io.Closeable interface in a number of places for Java 7 support. This means that you may not get warnings about unclosed iterators and other things. Watch for and pay attention to them. They are important. Java 7 is not required.
• To better support database partitioning, we made some changes to the ConnectionSource interface so now the table name is specified which allows the ConnectionSource to make decisions about which database to connect to depending on the table.
• We’ve made changes to Android to better support the java.sql.Timestamp and java.sql.Date as strings in the database. If you were using this types before you may have to add a persisterClass = TimeStampType.class or SqlDateType.class.
• We’ve removed a number of deprecated methods:
  • Dao.setAutoCommit(boolean), isAutoCommit()
  • QueryBuilder.clear(), limit(int), offset(int)
  • ForeignCollectionField.maxEagerForeignCollectionLevel(), foreignColumnName()
  • DatabaseFieldConfig.setMaxEagerForeignCollectionLevel(), setForeignCollectionMaxEagerForeignCollectionLevel(), setForeignCollectionOrderColumn(), setForeignCollectionForeignColumnName()
  • DataSourceConnectionSource.setUsesTransactions(boolean)
  • JdbcPooledConnectionSource.setUsesTransactions(boolean)
  • OpenHelperManager.release()
  • AndroidDatabaseResults(Cursor, boolean, ObjectCache) constructor

6.7 Notes About Version 4.49

The 4.49 release took a long time to put out unfortunately so it included a lot of changes, a couple of which need to be specifically enumerated. For more details, please check the change-log.

• Due to a couple of reporting issues, it was determined that some sort of locking was needed to protect concurrent usage of dao.callBatchTasks(...) calls from multiple threads when dealing with a single database connection. ORMLite now makes an attempt to detect a single-connection connection-source and will enforce locking so that only one batch task can be running at a time.
• A lot of changes were made to have CloseableIterator and other classes extend java.io.Closeable. If you are extending any of these classes then you may have to tweak your code.
• We fixed a problem with the maxForeignAutoRefreshLevel configuration setting which was particularly impacting Android users.

Again, please check the change-log for the entire list.

6.8 Upgrade to Version 4.45

To fix the date-string format bug introduced in version 4.43, I’ve decided to revert back to the date-string of yyyy-MM-dd HH:mm:ss.SSSSSS from the one introduced in 4.43 which was yyyy-MM-dd HH:mm:ss.SSS. This means that for folks doing date comparisons or using the version = true feature, if you have created data under 4.43 you will have to add the following to your date fields to make it work.

@DatabaseField(version = true, format="yyyy-MM-dd HH:mm:ss.SSS",
   dataType=DataType.DATE_STRING)
private Date date;

If you have data that was created both in 4.42 or before and 4.43 or 4.44 then you will have to convert some of the data. Something like the following UPDATE statement should work:

UPDATE your-table SET your-date-field =
    CONCAT(SUBSTRING(your-date-field, 1, 20), "000",
       SUBSTRING(your-date-field, 20, 3))
    WHERE LENGTH(your-date-field) = 23;

My sincere apologies for this mess up.

6.9 Problems With Version 4.43

In the process of looking into adding the timezone to the date-string, I made a change to the date-string format from yyyy-MM-dd HH:mm:ss.SSSSSS to yyyy-MM-dd HH:mm:ss.SSS – changing the milliseconds output from 6 digits to 3. This relatively small change broke the equality checking for date-strings which meant that Where.eq(...) and version = true field settings ceased to work correctly. The version processing code uses equality to verify that the object date is the same with the database and the new string value ...### is not equal to the old database format of ...######.

We have fixed this problem in 4.45 which reverts the string format. If you want to fix it permanently, you can use the format specifier on your date-string fields:

@DatabaseField(version = true, format="yyyy-MM-dd HH:mm:ss.SSSSSS",
   dataType=DataType.DATE_STRING)
private Date date;

My apologies for this problem.

6.10 Upgrade to Version 4.37

For Android users, in 4.37 we fixed a problem with the looking up of column names with imbedded periods in them by implementing our own lookup and not using the Android API. This had the unintended consequence of making the field name lookups be case sensitive. If you used ORMLite to generate your tables or if you used the @DatabaseField columnName to match the case then you would not be affected by this issue. But if you were working with an existing database with field names that did not match the case of the Java fields, then as of 4.37 you would be seeing the following exception.

java.sql.SQLException: Unknown field 'accountName' from the
    Android sqlite cursor, not in:[accountname, ...]"

Since other parts of the system are also case sensitive, we made the decision to not fix this problem but to encourage our users to properly use the @DatabaseField columnName if the case of your database does not match your Java fields. See columnName.

For example, before 4.37 your Android SQLite database might have the column accountname although your Java field might actually be accountName. As of 4.37, when you look up your Java fields you will have to add a columnName value like the following:

@DatabaseField(columnName = "accountname")
private String accountName;

We made the decision to force this change because there are other parts of ORMLite that are already case sensitive. For example, if you had mismatched case in your field names then using the dao.queryForMatching(obj) method would not work without the case matching the database. If you were building a custom query, you would have to say queryBuilder.where().eq("columnname", value) and could not use columnName.

Sorry for not recognizing this incompatibility earlier.

6.11 Upgrade to Version 4.30

For Android users, in 4.30 we added some reflection hacks to make the processing of the @DatabaseField annotations a lot faster. For this reason the following changes must be made:

• Instead of calling the annotation methods directly which causes tons of unnecessary GC objects, we use reflection and build a DatabaseTableConfig instead. This means that if you have defined custom Dao classes, you will need to add a new constructor:

  public class AccountDaoImpl extends BaseDaoImpl<Account, String> implements AccountDao { public AccountDaoImpl(ConnectionSource connectionSource) throws SQLException { super(connectionSource, Account.class); } // NOTE: this constructor is needed under Android in 4.30 public AccountDaoImpl(ConnectionSource connectionSource, DatabaseTableConfig<Account> tableConfig) throws SQLException { super(connectionSource, tableConfig); } }

• Because we had to write specific code to reflect on the @DatabaseField annotation we have deprecated the @DatabaseFieldSimple and other annotations that were added in version 4.26. Sorry for the reversal on this but they were also causing confusion.

6.12 Upgrade to Version 4.20

In 4.20 we made a couple of changes that bear some note.

• For Android developers, we significantly improved the mechanism for injecting the class of the database open helper. Setting the class name in the strings.xml resource file is still supported although it is not necessary if you are using OrmLiteBaseActivity or the other base classes. If you are extending those classes, ORMLite will detect the helper class automagically. The SqliteOpenHelperFactory mechanism, although still supported, has been deprecated. See database open helper wiring.
• We added the uniqueCombo setting for uniqueness across field combinations. We also changed the SQL that was generated if you are using the unique setting. The old SQL was correct but the new versions are more compatible with the SQL standard and the various database types. See unique constraints.
• We did some memory audits of ORMLite and improved the way that we were using DAOs internally so that we use cached DAOs where possible. We also improved the memory usage with foreign fields and some of the TableUtil methods. Thanks much to various folks on the user list who significantly helped with this process.

6.13 Upgrade to Version 4.14

In 4.14 we added a DatabaseType.BYTE_ARRAY which stores byte[] directly. See BYTE_ARRAY. In the past, this array would have been stored as a serialized array of bytes. To not break backwards compatibility with the database, fields with the byte[] type must now specify either the BYTE_ARRAY or SERIALIZABLE types using the dataType field on @DatabaseField – it will not be chosen automatically. See DatabaseField dataType. If we did not do this then previously stored data would be read from the database improperly.

In addition, serialized types must also now specify their dataType value. You should use DataType.SERIALIZABLE to continue to store serialized objects in the database. This will allow us to add direct support for other serialized types in the future without breaking backwards compatibility.

If you already have Serializable data (byte[] or other objects) stored in a database then you will need to add something like the following to your fields:

@DatabaseField(dataType = DataType.SERIALIZABLE)
Serializable field;

For newly stored byte[] fields, you could use the BYTE_ARRAY type to store the bytes directly. But any existing data will not be converted automatically.

@DatabaseField(dataType = DataType.BYTE_ARRAY)
byte[] field;

6.14 Upgrade to Version 4.10

4.10 was a reasonably large release containing some feature upgrades and some bug fixes. No data formats were changed, however the following API code was altered:

• We significantly refactored the RawResults class which is now deprecated and replaced it with the GenericRawResults class. See the GenericRawResults for more information. See section Issuing Raw Queries.
• The Dao methods queryForAllRaw() and iteratorRaw() are now deprecated. They are replaced with queryRaw(...) methods. See the Dao class javadocs for more information.
• Before this release the -jdbc and -android versions of ORMLite contained the -core functionality. In this release we split out the -core from the other packages so you will now need to install both the core and android (or jdbc) packages to get the package to work.

6.15 Upgrade to Version 4.0

No data formats were changed, however the following API code was altered. Removed any outside usage of the DatabaseType since the ConnectionSource now provides it. Also added features to be able to prepare update and delete statements. To provide type safety, we’ve moved back to using QueryBuilder so we can have UpdateBuilder and DeleteBuilder. And instead of a PreparedStmt there is PreparedQuery, PreparedUpdate, and PreparedDelete. Here are the details:

• We have removed most of the cases where the user has to deal with the DatabaseType. All you need to set on the DAOs is the ConnectionSource which provides the database type internally. To create and drop the tables, also, you only need the ConnectionSource.
• Constructing a BaseDaoImpl now self-initializes if it is constructed with a ConnectionSource. This validates the class configurations meaning that it now throws a SQLException.
• Constructing a JdbcConnectionSource or DataSourceConnectionSource also now throws a SQLException since they also now self-initialize if they are constructed with the URL. This creates the internal database type and loads the driver class for it.
• Deprecated the createJdbcConnectionSource method in the DatabaseTypeUtils and turned the loadDriver method into a no-op. You now just instantiate the JdbcConnectionSource directly and there is no need for referencing the DatabaseTypeUtils anymore.
• Dao.statementBuilder() method changed (back) to Dao.queryBuilder().
• Dao.queryBuilder() returns a QueryBuilder instead of a StatementBuilder.
• You now call distinct(), limit() and offset() on the QueryBuilder. Unfortunately, there are no deprecated methods for them on the StatementBuilder.
• You now call selectColumns() on the QueryBuilder instead of columns() since now we have columns also in the UpdateBuilder. Unfortunately, there are no deprecated methods for them on the StatementBuilder.
• You call QueryBuilder.prepare() instead of StatementBuilder.prepareStatement(). It returns a PreparedQuery instead of a PreparedStmt. You pass a PreparedQuery into the Dao.query() and Dao.iterator() methods instead of a PreparedStmt.
• We removed the DatabaseTypeFactory class since it was no longer needed for Spring configurations.
• Removed BaseJdbcDao since it had been deprecated in 3.X.

6.16 Upgrade to Version 3.2

The 3.2 release involved a very large code reorganization and migration. There were no on-disk changes unless you somehow managed to get ORMLite working previously on Android. The project was basically split into 3 pieces: core functionality, JDBC database handlers, and the new Android handler. With significant help from Kevin G, we abstracted all of the database calls into 3 interfaces: ConnectionSource (like a DataSource), DatabaseConnection (like a Connection) and DatabaseResults (like a ResultSet). Once we had the interfaces in place, we wrote delegation classes for JDBC and Android handlers. This means that as of 3.X we release 3 packages: ormlite-core (for developers), ormlite-jdbc (for people connecting to JDBC databases), and ormlite-android (for Android users). Both the JDBC and Android packages include all of the core code as well.

Along the way a number of specific changes were made to the methods and classes:

• Since we split off the JDBC, we renamed the BaseJdbcDao to be BaseDaoImpl in the core package. You will need to adjust any DAOs that you have.
• We are in the process of allowing custom delete and update methods so we took the major upgrade opportunity to rename the QueryBuilder object to be StatementBuilder. NOTE: this was reverted later.
• Because of the above, we also renamed Dao.queryBuilder() method to be statementBuilder(). NOTE: this was reverted later.
• Also renamed the PreparedQuery object to be PreparedStmt.
• One of the big changes for those of you using an external JDBC DataSource is that you no longer set it on the DAO directly. You need to wrap your DataSource in a DataSourceConnectionSource wrapper class which gets set on the DAO instead.

Again, there were no on-disk changes unless you somehow managed to get ORMLite working previously on Android. Since we were using JDBC before to do the data marshaling and now are doing it by hand, some of the data representations may have changed. Sorry for the lack of detail here.

6.17 Upgrade to Version 2.4

A bug was fixed in 2.4 with how we were handling Derby and Hsqldb. Both of these databases seem to be capitalizing table and field names in certain situations which meant that customized queries of ORMLite generated tables were affected. In version 2.4, all tables and field names are capitalized in the SQL generated for Derby and Hsqldb databases. This means that if you have data in these databases from a pre 2.4 version, the 2.4 version will not be able to find the tables and fields without renaming to be uppercase.

7. Example Code

Here is some example code to help you get going with ORMLite. I often find that code is the best documentation of how to get something working. Please feel free to suggest additional example packages for inclusion here. Source code submissions are welcome as long as you don’t get piqued if we don’t chose your’s.

7.1 JDBC Examples

All of the JDBC examples below depend on the H2 database which is a native Java SQL implementation. You can download the latest jar from the website.

Simple, basic

This is a simple application which performs database operations on a single class/table. See the source code.

Foreign objects

This example shows how to use foreign objects. See section Foreign Object Fields. See the source code.

Foreign collections

This example shows how to use foreign collections. See section Foreign Collections. See the source code.

Field configuration

This example shows how you can configure a class in ORMLite using Java code instead of annotations. See section Class Configuration. See the source code.

Many to many

This example is a bit more complicated with multiple tables and is designed for folks trying to model a many-to-many relationship. It has a join-table, foreign fields, and also utilizes inner queries. See the source code.

Spring wiring

To demonstrate how to use Spring wiring with ORMLite, this little program includes classes and XML configuration files. See the source code.

Data persister

This example shows how to define custom data persisters with ORMLite which can change how data types are stored in the database. See the source code.

7.2 Android Examples

For Android developers, here some complete example application projects to help you get started. See here for tarballs of all of the packages as well as code links.

HelloAndroid

A basic Android application which does some database operations and then quits.

ClickCounter

A nice little application written by Kevin G. that provides a counter type application using ORMLite.

NotifyService

An example of a service application that uses ORMLite written by Kevin G.

HelloAndroidH2

This is similar to the HelloAndroid example but it is using JDBC and H2 instead of the build-in Android database calls. This is more a proof of concept rather than a true example. The wiring for the onCreate and onUpdate is a hack. H2 is certainly larger, has tons more features, but is slower than the native SQLite. Also, JDBC under Android is not completely sanctioned by Google and support for it may be removed in the future.

HelloAndroidNoBase

This is similar to the HelloAndroid example but its activity does not extend the OrmLiteBaseActivity but instead manages the helpers itself. Certain programmers may want to manage the database connections using their own code to better share between activities and services or to use ORMLite when it is not possible to extend the base classes.

HelloAndroidTwoDbs

This is similar to the HelloAndroid example but it uses two separate databases, manages the helpers itself, and does not use the OpenHelperManager to manage the helpers at all. This is one way that you can deal with two different databases.

8. Contributions

There are a number of people who have helped with this project. If I’ve forgotten you please remind me so I can add you to this list. Let me know if you’d like to tune your name or add link to your home page here as well.

Thanks much to them all.

• Kevin Galligan was the impetus and the author of a good bit of the Android compatible code. He wrote the Android level support classes and did a ton of beta-testing of it. He’s also provided the initial Android examples. See http://www.kagii.com/.
• JC Romanda has been an excellent addition to the user base providing feedback, discovering and reporting bugs, providing patches for new features, testing new features before the release, and thinking a lot about how ORMLite can be extended and improved.
• Nelson Erb was our self-appointed documentation and testing volunteer for a year. He did a great job summarizing sections of this document so we could create a better ’Getting Started’ section. He also fleshed out a bunch of unit tests to improve coverage.
• Craig Andrews and Pedro Velasco has been very quick with feedback, bug reports, feature requests and other help.
• Jim Gloor was one of the Java gurus at a previous company. His great object instincts and the JDBC code samples helped start this project.
• Robert Adamsky was a colleague of mine at a company where he laid out our entire DAO and hibernate class hierarchy. The DAO interface and the BaseDaoImpl where in some part modeled after his code.
• Thanks much to the following folks for their bug reports, unit test submissions, memory analysis, code samples, feature requests, improvements, and general feedback: 51mon, Adam Brown, AlexPal, Ali Aksakarya, Andre, Andrea Sprega, Andreas, Andrew Sleeman, Andrew8er, Andrey, Anthony Whitlock, Bart, Ben Mosher, Candlejack, Carlos Fonseca, Casey, Chad Schultz, Chase, Chris Banes, Chris Nevill, Christian Ruppert, Dale Asberry, Daniel Colchete, Daniel Jette, Diederik, Eric Fung, Evan Grim, Farrukh Najmi, Filipe Leandro, Flo, Guillermo Campelo, HeDYn, Howard Liberty, Ian Dees, Javier Hinmel, Jaxelrod, Jaykob, Jean-Maxime Pelletier, Jeremy Mcjunkin, Jeremy Stone, Jeroen Rakhorst, Joao Bosco, John Kristian, Johny Jugianto, Jomble, Jonathan Caryl, Joseph Jones, Josh Guilfoyle, Kaan, Kyle Lampert, Larry Hamel, Lder, Livelazily, Lstrzelecki, Luke Meyer, ManosProm, Mariak Kalman, Mark Rogers, Markus Wiederkehr, Mathias Lin, Micael Dahlgren, Michael, Michael Weimann, Ming Lin, Miroslav Nadhajsky, Mohammad Moghimi, Nathan Jones, Natinusala, Nick Campion, Nonameplum, Outofrange, Patras Vlad, Pavel Arnost, Patrick, Pedro Velasco, Rahan, Ramps, Richard Kooijman, Roger Keays, Roland Oldenburg, Roman Zimmer, Sebastian Roth, Skylar, Slava Tysianchuk, Spacetime, Stephen Couchman, Stew, Stewert, Timo, Tom Tantisalidchai, Tony, Tonyxiao, Tsharp, VincentFTS, Vladimir, Wayne Stidolph, Wener, Yossi Wasserman, Birbird, Coder sam, Glenviewjeff, Igromanru, Jon, Mjomble, Nybblr, Shikajiro, Steffen, Zachawilson .

Thanks much to them all.

9. ISC Open Source License

This document is part of the ORMLite project.

Copyright 2021, Gray Watson

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Index of Concepts