Copyright (c) 2008 - 2015 Oracle Corporation. 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:
Petros Splinakis - Java Persistence 2.2
Linda DeMichiel - Java Persistence 2.1
Linda DeMichiel - Java Persistence 2.0
/*******************************************************************************
* Copyright (c) 2008 - 2015 Oracle Corporation. 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:
* Petros Splinakis - Java Persistence 2.2
* Linda DeMichiel - Java Persistence 2.1
* Linda DeMichiel - Java Persistence 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 Also: Since: Java Persistence 1.0
/**
* Specifies a column for joining an entity association or element
* collection. If the <code>JoinColumn</code> annotation itself is
* defaulted, a single join column is assumed and the default values
* apply.
*
* <pre>
* 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;}
* </pre>
*
* @see ManyToOne
* @see OneToMany
* @see OneToOne
* @see JoinTable
* @see CollectionTable
* @see ForeignKey
*
* @since Java Persistence 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.
/**
* (Optional) The name of the foreign key column.
* The table in which it is found depends upon the
* context.
* <ul>
* <li>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.
* <li> 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.
* <li> 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.
* <li> If the join is for an element collection, the foreign
* key is in a collection table.
*</ul>
*
* <p> 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.
/**
* (Optional) The name of the column referenced by this foreign
* key column.
* <ul>
* <li> When used with entity relationship mappings other
* than the cases described here, the referenced column is in the
* table of the target entity.
* <li> When used with a unidirectional OneToMany foreign key
* mapping, the referenced column is in the table of the source
* entity.
* <li> When used inside a <code>JoinTable</code> 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.
* <li> When used in a <code>CollectionTable</code> mapping, the
* referenced column is in the table of the entity containing the
* collection.
* </ul>
*
* <p> 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.
/**
* (Optional) Whether the property is a unique key. This is a
* shortcut for the <code>UniqueConstraint</code> 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. /** (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.
/**
* (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.
/**
* (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.
/**
* (Optional) The SQL fragment that is used when
* generating the DDL for the column.
* <p> 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.
/**
* (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.
*
* <p> Default:
* <ul>
* <li> 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.
* <li> If the join is for a unidirectional OneToMany mapping
* using a foreign key mapping strategy, the name of the table of
* the target entity.
* <li> 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.
* <li> If the join is for an element collection, the name of the collection table.
* </ul>
*/
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 Java Persistence 2.1
/**
* (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 Java Persistence 2.1
*/
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}