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/*
 * 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:
//     Petros Splinakis - 2.2
//     Linda DeMichiel - 2.0 - Version 2.0 (October 1 - 2013)
//     Specification available from https://projects.eclipse.org/projects/ee4j.jpa

package jakarta.persistence;

import java.lang.annotation.Repeatable;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static jakarta.persistence.ConstraintMode.PROVIDER_DEFAULT;

/**
 * Used to override a mapping for an entity relationship.
 *
 * 

May be applied to an entity that extends a mapped superclass * to override a relationship mapping defined by the mapped superclass. * If not specified, the association is mapped the same as in the * original mapping. When used to override a mapping defined by a * mapped superclass, {@code AssociationOverride} is applied to the * entity class. * *

May be used to override a relationship mapping from an * embeddable within an entity to another entity when the embeddable * is on the owning side of the relationship. When used to override a * relationship mapping defined by an embeddable class (including an * embeddable class embedded within another embeddable class), * {@code AssociationOverride} is applied to the field or property * containing the embeddable. * *

When {@code AssociationOverride} is used to override a * relationship mapping from an embeddable class, the {@link #name} * element specifies the referencing relationship field or property * within the embeddable class. To override mappings at multiple * levels of embedding, a dot ({@code .}) notation syntax must be used * in the {@code name} element to indicate an attribute within an * embedded attribute. The value of each identifier used with the dot * notation is the name of the respective embedded field or property. * *

When {@code AssociationOverride} is applied to override the * mappings of an embeddable class used as a map value, "{@code value.}" * must be used to prefix the name of the attribute within the embeddable * class that is being overridden in order to specify it as part of the * map value. * *

If the relationship mapping is a foreign key mapping, the * {@link #joinColumns} element is used. If the relationship mapping * uses a join table, the {@link #joinTable} element must be specified * to override the mapping of the join table and/or its join columns. * *

Example 1: Overriding the mapping of a relationship defined by a * mapped superclass * {@snippet : * @MappedSuperclass * public class Employee { * ... * @ManyToOne * protected Address address; * ... * } * * @Entity * @AssociationOverride(name = "address", * joinColumns = @JoinColumn(name = "ADDR_ID")) * // address field mapping overridden to ADDR_ID foreign key * public class PartTimeEmployee extends Employee { * ... * } * } * *

Example 2: Overriding the mapping for {@code phoneNumbers} defined * in the {@code ContactInfo} class * {@snippet : * @Entity * public class Employee { * @Id int id; * @AssociationOverride( * name = "phoneNumbers", * joinTable = @JoinTable(name = "EMPPHONES", * joinColumns = @JoinColumn(name = "EMP"), * inverseJoinColumns = @JoinColumn(name = "PHONE"))) * @Embedded * ContactInfo contactInfo; * ... * } * * @Embeddable * public class ContactInfo { * @ManyToOne * Address address; // Unidirectional * @ManyToMany(targetEntity = PhoneNumber.class) * List phoneNumbers; * } * * @Entity * public class PhoneNumber { * @Id * int number; * @ManyToMany(mappedBy = "contactInfo.phoneNumbers") * Collection employees; * } * } * * @see Embedded * @see Embeddable * @see MappedSuperclass * @see AttributeOverride * * @since 1.0 */ @Repeatable(AssociationOverrides.class) @Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME) public @interface AssociationOverride { /** * (Required) The name of the relationship property whose mapping * is being overridden if property-based access is being used, * or the name of the relationship field if field-based access is * used. */ String name(); /** * The join column(s) being mapped to the persistent attribute(s). * The {@code joinColumns} elements must be specified if a foreign * key mapping is used in the overriding of the mapping of the * relationship. The {@code joinColumns} element must not be * specified if a join table is used in the overriding of the * mapping of the relationship. */ JoinColumn[] joinColumns() default {}; /** * (Optional) Used to specify or control the generation of a * foreign key constraint for the columns corresponding to the * {@code joinColumns} element when table generation is in effect. * If both this element and the {@code foreignKey} element of any * of the {@code joinColumns} 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 2.1 */ ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT); /** * The join table that maps the relationship. * The {@code joinTable} element must be specified if a join table * is used in the overriding of the mapping of the relationship. * The {@code joinTable} element must not be specified if a foreign * key mapping is used in the overriding of the relationship. * * @since 2.0 */ JoinTable joinTable() default @JoinTable; }





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