javax.persistence.MapsId Maven / Gradle / Ivy
/*
* Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution. The Eclipse Public License is available
* at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
* is available at http://www.eclipse.org/org/documents/edl-v10.php.
*/
package javax.persistence;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Designates a ManyToOne or OneToOne relationship attribute that provides the
* mapping for an {@link EmbeddedId} primary key, an attribute within an EmbeddedId primary key,
* or a simple primary key of the parent entity. The value element specifies the attribute within
* a composite key to which the relationship attribute corresponds. If the entity's primary key is of the same
* Java type as the primary key of the entity referenced by the relationship, the value attribute is not
* specified.
*
*
* Example:
*
* // parent entity has simple primary key
*
* @Entity
* public class Employee {
* @Id long empId;
* String name;
* ...
* }
*
* // dependent entity uses EmbeddedId for composite key
*
* @Embeddable
* public class DependentId {
* String name;
* long empid; // corresponds to primary key type of Employee
* }
*
* @Entity
* public class Dependent {
* @EmbeddedId DependentId id;
* ...
* @MapsId("empid") // maps the empid attribute of embedded id
* @ManyToOne Employee emp;
* }
*
*
* @since Java Persistence 2.0
*/
@Target({FIELD})
@Retention(RUNTIME)
public @interface MapsId {
/**
* (Optional) The name of the attribute within the composite key to which the relationship attribute
* corresponds. If not supplied, the relationship maps the entitys primary key.
*
* @return name
*/
String value() default "";
}