jakarta.persistence.IdClass 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.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Specifies a composite primary key type whose fields or
* properties map to the {@linkplain Id identifier} fields
* or properties of the annotated entity class.
*
* The specified primary key type must:
*
* - be a non-{@code abstract} regular Java class, or a
* Java record type,
*
- have a {@code public} or {@code protected} constructor
* with no parameters, unless it is a record type, and
*
- implement {@link #equals} and {@link #hashCode}, defining
* value equality consistently with equality of the mapped
* primary key of the database table.
*
*
* The primary key fields of the entity must be annotated
* {@link Id}, and the specified primary key type must have
* fields or properties with matching names and types. The
* mapping of fields or properties of the entity to fields
* or properties of the primary key class is implicit. The
* primary key type does not itself need to be annotated.
*
*
Example:
* {@snippet :
* @IdClass(EmployeePK.class)
* @Entity
* public class Employee {
* @Id
* String empName;
* @Id
* Date birthDay;
* ...
* }
*
* public record EmployeePK(String empName, Date birthDay) {}
* }
*
* @see EmbeddedId
*
* @since 1.0
*/
@Target({TYPE})
@Retention(RUNTIME)
public @interface IdClass {
/**
* The primary key class, which must declare fields or
* properties with names and types that match the
* {@link Id} fields and properties of the annotated
* entity class.
*/
Class value();
}