jakarta.persistence.EmbeddedId Maven / Gradle / Ivy
/*
* Copyright (c) 2008, 2023 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Linda DeMichiel - 2.1
// Linda DeMichiel - 2.0
package jakarta.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;
/**
* Specifies that the annotated persistent field or property
* of an entity class or mapped superclass is the composite
* primary key of the entity. The type of the annotated field
* or property must be an {@linkplain Embeddable embeddable}
* type, and must be explicitly annotated {@link Embeddable}.
*
* If a field or property of an entity class is annotated
* {@code EmbeddedId}, then no other field or property of the
* entity may be annotated {@link Id} or {@code EmbeddedId},
* and the entity class must not declare an {@link IdClass}.
*
*
The embedded primary key type must implement
* {@link #equals} and {@link #hashCode}, defining value
* equality consistently with equality of the mapped primary
* key of the database table.
*
*
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 {@code EmbeddedId} annotation to declare a derived
* primary key.
*
*
If the entity has a derived primary key, the
* {@link 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 primary
* key type are not supported.
*
*
Example 1:
* {@snippet :
* @Entity
* public class Employee {
* @EmbeddedId
* protected EmployeePK empPK;
* ...
* }
*
* public record EmployeePK(String empName, Date birthDay) {}
* }
*
*
Example 2:
* {@snippet :
* @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 = @Column(name = "dep_name"))
* @EmbeddedId
* DependentId id;
* ...
* @MapsId("empPK")
* @ManyToOne
* Employee emp;
* }
* }
*
* @see Embeddable
* @see MapsId
* @see IdClass
*
* @since 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface EmbeddedId {}