javax.persistence.ForeignKey Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of javax.persistence Show documentation
javax.persistence build based upon git transaction cfcdce1
The newest version!
/*
 * Copyright (c) 2011, 2018 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 - Java Persistence 2.1

package javax.persistence;

import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static javax.persistence.ConstraintMode.CONSTRAINT;

/**
 * Used to specify the handling of foreign key constraints when schema
 * generation is in effect.  If this annotation is not specified, the
 * persistence provider's default foreign key strategy will be used.
 * 
 * The ConstraintMode value is used to specify whether foreign
 * key constraints should be generated.
 * 

 * The syntax used in the foreignKeyDefinition element 
 * should follow the SQL syntax used by the target database for foreign
 * key constraints.  For example, this may be similar the following:
 * 
 * FOREIGN KEY ( <COLUMN expression> {, <COLUMN expression>}... )
 * REFERENCES <TABLE identifier> [
 *     (<COLUMN expression> {, <COLUMN expression>}... ) ]
 * [ ON UPDATE <referential action> ]
 * [ ON DELETE <referential action> ]
 * 
 *
 * When the ConstraintMode value is
 * CONSTRAINT, but the foreignKeyDefinition
 * element is not specified, the provider will generate foreign key
 * constraints whose update and delete actions it determines most
 * appropriate for the join column(s) to which the foreign key
 * annotation is applied.
 *
 * @see JoinColumn
 * @see JoinColumns
 * @see MapKeyJoinColumn
 * @see MapKeyJoinColumns
 * @see PrimaryKeyJoinColumn
 * @see JoinTable
 * @see CollectionTable
 * @see SecondaryTable
 * @see AssociationOverride
 *
 * @since Java Persistence 2.1
 */
@Target({})
@Retention(RUNTIME)
public @interface ForeignKey {

    /**
     * (Optional) The name of the foreign key constraint.  If this
     * is not specified, it defaults to a provider-generated name.
     */
    String name() default "";

    /**
     * (Optional) Used to specify whether a foreign key constraint should be
     *  generated when schema generation is in effect. 
     *  
     *  A value of CONSTRAINT will cause the persistence
     *  provider to generate a foreign key constraint.  If the
     *  foreignKeyDefinition element is not specified, the
     *  provider will generate a constraint whose update
     *  and delete actions it determines most appropriate for the
     *  join column(s) to which the foreign key annotation is applied.
     *  

     *  A value of NO_CONSTRAINT will result in no
     *  constraint being generated.
     *  
     *  A value of PROVIDER_DEFAULT will result in the
     *  provider's default behavior (which may or may not result
     *  in the generation of a constraint for the given join column(s).
     */
    ConstraintMode value() default CONSTRAINT;

    /**
     * (Optional) The foreign key constraint definition.  
     */
    String foreignKeyDefinition() default "";
}