javax.persistence.EmbeddedId Maven / Gradle / Ivy
// $Id: EmbeddedId.java 17752 2009-10-15 01:19:21Z [email protected] $
// EJB3 Specification Copyright 2004-2009 Sun Microsystems, Inc.
package javax.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Applied to a persistent field or property of an entity
* class or mapped superclass to denote a composite primary
* key that is an embeddable class. The embeddable class
* must be annotated as {@link Embeddable}.
*
* There must be only one EmbeddedId annotation and
* no Id annotation when the EmbeddedId annotation is used.
*
*
The {@link AttributeOverride} annotation may be used to override
* the column mappings declared within the embeddable class.
*
*
The {@link MapsId} annotation may be used in conjunction
* with the EmbeddedId annotation to specify a derived
* primary key.
*
*
If the entity has a derived primary key, the
* AttributeOverride annotation may only be used to
* override those attributes of the embedded id that do not correspond
* to the relationship to the parent entity.
*
*
Relationship mappings defined within an embedded id class are not supported.
*
*
* Example 1:
*
* @EmbeddedId
* protected EmployeePK empPK;
*
*
* Example 2:
*
* @Embeddable
* public class DependentId {
* String name;
* EmployeeId empPK; // corresponds to primary key type of Employee
* }
*
* @Entity
* public class Dependent {
* // default column name for "name" attribute is overridden
* @AttributeOverride(name="name", @Column(name="dep_name"))
* @EmbeddedId DependentId id;
* ...
* @MapsId("empPK")
* @ManyToOne Employee emp;
* }
*
*
* @see Embeddable
* @see MapsId
*
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface EmbeddedId {
}