EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Default Conversions and Converters/TypeConverter

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@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;
 }

This table lists attributes of the @TypeConverter annotation.

Attribute Description Default Required or Optional

name

Set this attribute to the String name for your converter. Ensure that this name is unique across the persistence unit.

no default

required

dataType

Set this attribute to the type stored in the database.

void.class1

optional

objectType

Set the value of this attribute to the type stored on the entity.

void.class1

optional


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;
     }
     ...
 }



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