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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Default Conversions and Converters/TypeConverter"
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The <tt>@TypeConverter</tt> is an EclipseLink-specific annotation. You can use it to specify an <tt>org.eclipse.persistence.mappings.converters.TypeConversionConverter</tt> for modification of the data value(s) during the reading and writing of a mapped attribute. | The <tt>@TypeConverter</tt> is an EclipseLink-specific annotation. You can use it to specify an <tt>org.eclipse.persistence.mappings.converters.TypeConversionConverter</tt> for modification of the data value(s) during the reading and writing of a mapped attribute. |
Revision as of 10:39, 31 January 2011
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Key API TypeConverter
@TypeConverter Annotation and <type-converter> XML
The @TypeConverter is an EclipseLink-specific annotation. You can use it to specify an org.eclipse.persistence.mappings.converters.TypeConversionConverter for modification of the data value(s) during the reading and writing of a mapped attribute.
@Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME) public @interface TypeConverter { String name(); Class dataType() default void.class; Class objectType() default void.class; }
Attribute | Description | Default | Required? |
---|---|---|---|
name | Set this attribute to the String name for your converter. Ensure that this name is unique across the persistence unit. | Yes | |
dataType | Set this attribute to the type stored in the database. | void.class1 | No |
objectType | Set the value of this attribute to the type stored on the entity. | void.class1 | No |
1 The default is inferred from the type of the persistence field or property.
This example shows how to use the @TypeConverter annotation to convert the Double value stored in the database to a Float value stored in the entity.
Usage of the @TypeConverter Annotation
@Entity public class Employee implements Serializable{ ... @TypeConverter ( name="doubleToFloat", dataType=Double.class, objectType=Float.class, ) @Convert("doubleToFloat") public Number getGradePointAverage() { return gradePointAverage; } ... }