javax.persistence.ManyToOne Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2008, 2009 Sun Microsystems. 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.
*
* Contributors:
* Linda DeMichiel - Java Persistence 2.0 - Version 2.0 (October 1, 2009)
* Specification available from http://jcp.org/en/jsr/detail?id=317
*
******************************************************************************/
package javax.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import javax.persistence.CascadeType;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.FetchType.EAGER;
/**
* Defines a single-valued association to another entity class that
* has many-to-one multiplicity. It is not normally necessary to
* specify the target entity explicitly since it can usually be
* inferred from the type of the object being referenced. If the
* relationship is bidirectional, the non-owning
* OneToMany entity side must used the
* mappedBy element to specify the relationship field or
* property of the entity that is the owner of the relationship.
*
* The ManyToOne annotation may be used within an
* embeddable class to specify a relationship from the embeddable
* class to an entity class. If the relationship is bidirectional, the
* non-owning OneToMany entity side must use the mappedBy
* element of the OneToMany annotation to specify the
* relationship field or property of the embeddable field or property
* on the owning side of the relationship. The dot (".") notation
* syntax must be used in the mappedBy element to indicate the
* relationship attribute within the embedded attribute. The value of
* each identifier used with the dot notation is the name of the
* respective embedded field or property.
*
*
* Example 1:
*
* @ManyToOne(optional=false)
* @JoinColumn(name="CUST_ID", nullable=false, updatable=false)
* public Customer getCustomer() { return customer; }
*
*
* Example 2:
*
* @Entity
* public class Employee {
* @Id int id;
* @Embedded JobInfo jobInfo;
* ...
* }
*
* @Embeddable
* public class JobInfo {
* String jobDescription;
* @ManyToOne ProgramManager pm; // Bidirectional
* }
*
* @Entity
* public class ProgramManager {
* @Id int id;
* @OneToMany(mappedBy="jobInfo.pm")
* Collection<Employee> manages;
* }
*
*
*
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface ManyToOne {
/**
* (Optional) The entity class that is the target of
* the association.
*
* Defaults to the type of the field or property
* that stores the association.
*/
Class targetEntity() default void.class;
/**
* (Optional) The operations that must be cascaded to
* the target of the association.
*
*
By default no operations are cascaded.
*/
CascadeType[] cascade() default {};
/**
* (Optional) Whether the association should be lazily
* loaded or must be eagerly fetched. The EAGER
* strategy is a requirement on the persistence provider runtime that
* the associated entity must be eagerly fetched. The LAZY
* strategy is a hint to the persistence provider runtime.
*/
FetchType fetch() default EAGER;
/**
* (Optional) Whether the association is optional. If set
* to false then a non-null relationship must always exist.
*/
boolean optional() default true;
}