/*
* Copyright (c) 2008, 2009, 2011 Oracle, Inc. 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.
*/
package javax.persistence;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
Specifies a mapping to an entity that is a map key. The map key join column is in the collection table,
join table, or table of the target entity that is used to represent the map. If no
MapKeyJoinColumn annotation is specified, a single join column is assumed and the default
values apply.
Example 1:
@Entity
public class Company {
@Id int id;
...
@OneToMany // unidirectional
@JoinTable(name="COMPANY_ORGANIZATION",
joinColumns=@JoinColumn(name="COMPANY"),
inverseJoinColumns=@JoinColumn(name="VICEPRESIDENT"))
@MapKeyJoinColumn(name="DIVISION")
Map<Division, VicePresident> organization;
}
Example 2:
@Entity
public class VideoStore {
@Id int id;
String name;
Address location;
...
@ElementCollection
@CollectionTable(name="INVENTORY",
joinColumns=@JoinColumn(name="STORE"))
@Column(name="COPIES_IN_STOCK")
@MapKeyJoinColumn(name="MOVIE", referencedColumnName="ID")
Map<Movie, Integer> videoInventory;
...
}
@Entity
public class Movie {
@Id long id;
String title;
...
}
Example 3:
@Entity
public class Student {
@Id int studentId;
...
@ManyToMany // students and courses are also many-many
@JoinTable(name="ENROLLMENTS",
joinColumns=@JoinColumn(name="STUDENT"),
inverseJoinColumns=@JoinColumn(name="SEMESTER"))
@MapKeyJoinColumn(name="COURSE")
Map<Course, Semester> enrollment;
...
}
Since: Java Persistence 2.0
/**
* Specifies a mapping to an entity that is a map key. The map key join column is in the collection table,
* join table, or table of the target entity that is used to represent the map. If no
* <code>MapKeyJoinColumn</code> annotation is specified, a single join column is assumed and the default
* values apply.
* <p>
* <pre>
*
* Example 1:
*
* @Entity
* public class Company {
* @Id int id;
* ...
* @OneToMany // unidirectional
* @JoinTable(name="COMPANY_ORGANIZATION",
* joinColumns=@JoinColumn(name="COMPANY"),
* inverseJoinColumns=@JoinColumn(name="VICEPRESIDENT"))
* @MapKeyJoinColumn(name="DIVISION")
* Map<Division, VicePresident> organization;
* }
*
* Example 2:
*
* @Entity
* public class VideoStore {
* @Id int id;
* String name;
* Address location;
* ...
* @ElementCollection
* @CollectionTable(name="INVENTORY",
* joinColumns=@JoinColumn(name="STORE"))
* @Column(name="COPIES_IN_STOCK")
* @MapKeyJoinColumn(name="MOVIE", referencedColumnName="ID")
* Map<Movie, Integer> videoInventory;
* ...
* }
*
* @Entity
* public class Movie {
* @Id long id;
* String title;
* ...
* }
*
* Example 3:
*
* @Entity
* public class Student {
* @Id int studentId;
* ...
* @ManyToMany // students and courses are also many-many
* @JoinTable(name="ENROLLMENTS",
* joinColumns=@JoinColumn(name="STUDENT"),
* inverseJoinColumns=@JoinColumn(name="SEMESTER"))
* @MapKeyJoinColumn(name="COURSE")
* Map<Course, Semester> enrollment;
* ...
* }
* </pre>
*
* @since Java Persistence 2.0
*/
@Target({FIELD})
@Retention(RUNTIME)
@Repeatable(MapKeyJoinColumns.class)
public @interface MapKeyJoinColumn {
(Optional) The name of the foreign key column for the map key. The table in which it is found depends
upon the context.
- If the join is for a map key for an element collection, the foreign key column is in the collection
table for the map value.
- If the join is for a map key for a ManyToMany entity relationship or for a OneToMany entity
relationship using a join table, the foreign key column is in a join table.
- If the join is for a OneToMany entity relationship using a foreign key mapping strategy, the
foreign key column for the map key is in the table of the entity that is the value of the map.
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; "_";
"KEY".
Returns: The name
/**
* (Optional) The name of the foreign key column for the map key. The table in which it is found depends
* upon the context.
* <ul>
* <li>If the join is for a map key for an element collection, the foreign key column is in the collection
* table for the map value.
* <li>If the join is for a map key for a ManyToMany entity relationship or for a OneToMany entity
* relationship using a join table, the foreign key column is in a join table.
* <li>If the join is for a OneToMany entity relationship using a foreign key mapping strategy, the
* foreign key column for the map key is in the table of the entity that is the value of the map.
* </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; "_";
* "KEY".
*
* @return The name
*/
String name() default "";
(Optional) The name of the column referenced by this foreign key column. The referenced column is in
the table of the target entity.
Default (only applies if single join column is being used.) The same name as the primary key column of
the referenced table
Returns: The referenced col name
/**
* (Optional) The name of the column referenced by this foreign key column. The referenced column is in
* the table of the target entity.
* <p>
* Default (only applies if single join column is being used.) The same name as the primary key column of
* the referenced table
*
* @return The referenced col name
*/
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.
Returns: Whether unique
/**
* (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.
*
* @return Whether unique
*/
boolean unique() default false;
(Optional) Whether the foreign key column is nullable.
Returns: Whether nullable
/**
* (Optional) Whether the foreign key column is nullable.
*
* @return Whether nullable
*/
boolean nullable() default false;
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence
provider.
Returns: Whether insertable
/**
* (Optional) Whether the column is included in SQL INSERT statements generated by the persistence
* provider.
*
* @return Whether insertable
*/
boolean insertable() default true;
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence
provider.
Returns: Whether updateable
/**
* (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence
* provider.
*
* @return Whether updateable
*/
boolean updatable() default true;
(Optional) The SQL fragment that is used when generating the DDL for the column. Defaults to SQL
generated by the provider for the column.
Returns: The column definition
/**
* (Optional) The SQL fragment that is used when generating the DDL for the column. Defaults to SQL
* generated by the provider for the column.
*
* @return The column definition
*/
String columnDefinition() default "";
(Optional) The name of the table that contains the foreign key column.
- If the join is for a map key for an element collection, the foreign key column is in the collection
table for the map value.
- If the join is for a map key for a ManyToMany entity relationship or for a OneToMany entity
relationship using a join table, the foreign key column is in a join table.
- If the join is for a OneToMany entity relationship using a foreign key mapping strategy, the
foreign key column for the map key is in the table of the entity that is the value of the map.
Default:
- If the map is for an element collection, the name of the collection table for the map value.
- If the map is for a OneToMany or ManyToMany entity relationship using a join table, the name of the
join table for the map.
- If the map is for a OneToMany entity relationship using a foreign key mapping strategy, the name of
the primary table of the entity that is the value of the map.
Returns: The table
/**
* (Optional) The name of the table that contains the foreign key column.
* <ul>
* <li>If the join is for a map key for an element collection, the foreign key column is in the collection
* table for the map value.
* <li>If the join is for a map key for a ManyToMany entity relationship or for a OneToMany entity
* relationship using a join table, the foreign key column is in a join table.
* <li>If the join is for a OneToMany entity relationship using a foreign key mapping strategy, the
* foreign key column for the map key is in the table of the entity that is the value of the map.
* </ul>
* <p>
* Default:
* <ul>
* <li>If the map is for an element collection, the name of the collection table for the map value.
* <li>If the map is for a OneToMany or ManyToMany entity relationship using a join table, the name of the
* join table for the map.
* <li>If the map is for a OneToMany entity relationship using a foreign key mapping strategy, the name of
* the primary table of the entity that is the value of the map.
* </ul>
*
* @return The table
*/
String table() default "";
(Optional) The foreign key constraint specification for the join column. This is used only if table
generation is in effect. Default is provider defined.
Returns: The foreign key specification
/**
* (Optional) The foreign key constraint specification for the join column. This is used only if table
* generation is in effect. Default is provider defined.
*
* @return The foreign key specification
*/
ForeignKey foreignKey() default @ForeignKey();
}