javax.persistence.JoinColumn Maven / Gradle / Ivy
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/*
* Copyright (c) 2008, 2019 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 - 2.1
// Linda DeMichiel - 2.0
package javax.persistence;
import java.lang.annotation.Repeatable;
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 a column for joining an entity association or element
* collection. If the JoinColumn annotation itself is
* defaulted, a single join column is assumed and the default values
* apply.
*
*
* Example:
*
* @ManyToOne
* @JoinColumn(name="ADDR_ID")
* public Address getAddress() { return address; }
*
*
* Example: unidirectional one-to-many association using a foreign key mapping
*
* // In Customer class
* @OneToMany
* @JoinColumn(name="CUST_ID") // join column is in table for Order
* public Set<Order> getOrders() {return orders;}
*
*
* @see ManyToOne
* @see OneToMany
* @see OneToOne
* @see JoinTable
* @see CollectionTable
* @see ForeignKey
*
* @since 1.0
*/
@Repeatable(JoinColumns.class)
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface JoinColumn {
/**
* (Optional) The name of the foreign key column.
* The table in which it is found depends upon the
* context.
*
* - If the join is for a OneToOne or ManyToOne
* mapping using a foreign key mapping strategy,
* the foreign key column is in the table of the
* source entity or embeddable.
*
- If the join is for a unidirectional OneToMany mapping
* using a foreign key mapping strategy, the foreign key is in the
* table of the target entity.
*
- If the join is for a ManyToMany mapping or for a OneToOne
* or bidirectional ManyToOne/OneToMany mapping using a join
* table, the foreign key is in a join table.
*
- If the join is for an element collection, the foreign
* key is in a collection table.
*
*
* Default (only applies if a single join column is used):
* The concatenation of the following: the name of the
* referencing relationship property or field of the referencing
* entity or embeddable class; "_"; the name of the referenced
* primary key column.
* If there is no such referencing relationship property or
* field in the entity, or if the join is for an element collection,
* the join column name is formed as the
* concatenation of the following: the name of the entity; "_";
* the name of the referenced primary key column.
*/
String name() default "";
/**
* (Optional) The name of the column referenced by this foreign
* key column.
*
* - When used with entity relationship mappings other
* than the cases described here, the referenced column is in the
* table of the target entity.
*
- When used with a unidirectional OneToMany foreign key
* mapping, the referenced column is in the table of the source
* entity.
*
- When used inside a
JoinTable annotation,
* the referenced key column is in the entity table of the owning
* entity, or inverse entity if the join is part of the inverse
* join definition.
* - When used in a
CollectionTable mapping, the
* referenced column is in the table of the entity containing the
* collection.
*
*
* Default (only applies if single join column is being
* used): The same name as the primary key column of the
* referenced table.
*/
String referencedColumnName() default "";
/**
* (Optional) Whether the property is a unique key. This is a
* shortcut for the UniqueConstraint annotation at
* the table level and is useful for when the unique key
* constraint is only a single field. It is not necessary to
* explicitly specify this for a join column that corresponds to a
* primary key that is part of a foreign key.
*/
boolean unique() default false;
/** (Optional) Whether the foreign key column is nullable. */
boolean nullable() default true;
/**
* (Optional) Whether the column is included in
* SQL INSERT statements generated by the persistence
* provider.
*/
boolean insertable() default true;
/**
* (Optional) Whether the column is included in
* SQL UPDATE statements generated by the persistence
* provider.
*/
boolean updatable() default true;
/**
* (Optional) The SQL fragment that is used when
* generating the DDL for the column.
*
Defaults to the generated SQL for the column.
*/
String columnDefinition() default "";
/**
* (Optional) The name of the table that contains
* the column. If a table is not specified, the column
* is assumed to be in the primary table of the
* applicable entity.
*
*
Default:
*
* - If the join is for a OneToOne or ManyToOne mapping
* using a foreign key mapping strategy, the name of the table of
* the source entity or embeddable.
*
- If the join is for a unidirectional OneToMany mapping
* using a foreign key mapping strategy, the name of the table of
* the target entity.
*
- If the join is for a ManyToMany mapping or
* for a OneToOne or bidirectional ManyToOne/OneToMany mapping
* using a join table, the name of the join table.
*
- If the join is for an element collection, the name of the collection table.
*
*/
String table() default "";
/**
* (Optional) Used to specify or control the generation of a
* foreign key constraint when table generation is in effect. If
* this element is not specified, the persistence provider's
* default foreign key strategy will apply.
*
* @since 2.1
*/
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}