Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Default Conversions and Converters/TypeConverter"
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| − | + | The following example shows how to use the <tt>@TypeConverter</tt> annotation to convert the <tt>Double</tt> value stored in the database to a <tt>Float</tt> value stored in the entity. | |
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Revision as of 13:49, 29 March 2011
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Key API
TypeConverter
@TypeConverter Annotation
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.
The following 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.
Example: @TypeConverter Annotation
@Entity public class Employee implements Serializable{ ... @TypeConverter ( name="doubleToFloat", dataType=Double.class, objectType=Float.class, ) @Convert("doubleToFloat") public Number getGradePointAverage() { return gradePointAverage; } ... }
