src/javax/persistence/JoinTable.java

/*
 * Copyright (c) 2008, 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
//     Linda DeMichiel - Java Persistence 2.0

package javax.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;
import static javax.persistence.ConstraintMode.PROVIDER_DEFAULT;

/**
 * Specifies the mapping of associations. It is applied to the
 * owning side of an association.  
 *
 * <p> A join table is typically used in the mapping of many-to-many
 * and unidirectional one-to-many associations. It may also be used to
 * map bidirectional many-to-one/one-to-many associations,
 * unidirectional many-to-one relationships, and one-to-one
 * associations (both bidirectional and unidirectional).
 *
 *<p>When a join table is used in mapping a relationship with an
 *embeddable class on the owning side of the relationship, the
 *containing entity rather than the embeddable class is considered the
 *owner of the relationship.
 *
 * <p> If the <code>JoinTable</code> annotation is missing, the 
 * default values of the annotation elements apply.  
 * The name of the join table is assumed to be the table names of the 
 * associated primary tables concatenated together (owning side 
 * first) using an underscore.
 *
 * <pre>
 *
 *    Example:
 *
 *    &#064;JoinTable(
 *        name="CUST_PHONE",
 *        joinColumns=
 *            &#064;JoinColumn(name="CUST_ID", referencedColumnName="ID"),
 *        inverseJoinColumns=
 *            &#064;JoinColumn(name="PHONE_ID", referencedColumnName="ID")
 *    )
 * </pre>
 * 
 * @see JoinColumn
 * @see JoinColumns
 *
 * @since Java Persistence 1.0
 */
@Target({METHOD, FIELD}) 
@Retention(RUNTIME)

public @interface JoinTable {

    /**
     * (Optional) The name of the join table. 
     * 
     * <p> Defaults to the concatenated names of
     * the two associated primary entity tables, 
     * separated by an underscore.
     */
    String name() default "";

    /** (Optional) The catalog of the table. 
     * <p> Defaults to the default catalog.
     */
    String catalog() default "";

    /** (Optional) The schema of the table. 
     * <p> Defaults to the default schema for user.
     */
    String schema() default "";

    /**
     * (Optional) The foreign key columns
     * of the join table which reference the
     * primary table of the entity owning the
     * association. (I.e. the owning side of
     * the association).
     *
     * <p> Uses the same defaults as for {@link JoinColumn}.
     */
    JoinColumn[] joinColumns() default {};

    /** 
     * (Optional) The foreign key columns
     * of the join table which reference the
     * primary table of the entity that does
     * not own the association. (I.e. the
     * inverse side of the association).
     *
     * <p> Uses the same defaults as for {@link JoinColumn}.
     */
    JoinColumn[] inverseJoinColumns() default {};

    /**
     *  (Optional) Used to specify or control the generation of a
     *   foreign key constraint for the columns corresponding to the
     *   <code>joinColumns</code> element when table generation is in
     *   effect.  If both this element and the <code>foreignKey</code>
     *   element of any of the <code>joinColumns</code> elements are
     *   specified, the behavior is undefined.  If no foreign key
     *   annotation element is specified in either location, the
     *   persistence provider's default foreign key strategy will
     *   apply.
     *
     *  @since Java Persistence 2.1
     */
    ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);

    /**
     *  (Optional) Used to specify or control the generation of a
     *  foreign key constraint for the columns corresponding to the
     *  <code>inverseJoinColumns</code> element when table generation
     *  is in effect.  If both this element and the
     *  <code>foreignKey</code> element of any of the
     *  <code>inverseJoinColumns</code> elements are specified, the
     *  behavior is undefined.  If no foreign key annotation element
     *  is specified in either location, the persistence provider's
     *  default foreign key strategy will apply.
     *
     *  @since Java Persistence 2.1
     */
    ForeignKey inverseForeignKey() default @ForeignKey(PROVIDER_DEFAULT);

    /**
     * (Optional) Unique constraints that are
     * to be placed on the table. These are
     * only used if table generation is in effect.
     * <p> Defaults to no additional constraints.
     */
    UniqueConstraint[] uniqueConstraints() default {};

    /**
     * (Optional) Indexes for the table.  These are only used if
     * table generation is in effect. 
     *
     * @since Java Persistence 2.1 
     */
    Index[] indexes() default {};
}