javax.persistence.PrimaryKeyJoinColumn Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of hibernate-jpa-2.0-api Show documentation
Hibernate definition of the Java Persistence 2.0 (JSR 317) API.
There is a newer version: 1.0.1.Final
Show newest version
// $Id: PrimaryKeyJoinColumn.java 17752 2009-10-15 01:19:21Z [email protected] $
// EJB3 Specification Copyright 2004-2009 Sun Microsystems, Inc.
package javax.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Specifies a primary key column that is used as a foreign key to
 * join to another table.
 * 
 * It is used to join the primary table of an entity subclass
 * in the {@link InheritanceType#JOINED JOINED} mapping strategy
 * to the primary table of its superclass; it is used within a
 * {@link SecondaryTable} annotation to join a secondary table
 * to a primary table; and it may be used in a {@link OneToOne}
 * mapping in which the primary key of the referencing entity
 * is used as a foreign key to the referenced entity.
 * 

 * If no PrimaryKeyJoinColumn annotation is
 * specified for a subclass in the JOINED
 * mapping strategy, the foreign key columns are assumed
 * to have the same names as the primary key columns of the
 * primary table of the superclass.
 *
 * 
 *
 *    Example: Customer and ValuedCustomer subclass
 *
 *    @Entity
 *    @Table(name="CUST")
 *    @Inheritance(strategy=JOINED)
 *    @DiscriminatorValue("CUST")
 *    public class Customer { ... }
 *
 *    @Entity
 *    @Table(name="VCUST")
 *    @DiscriminatorValue("VCUST")
 *    @PrimaryKeyJoinColumn(name="CUST_ID")
 *    public class ValuedCustomer extends Customer { ... }
 * 
 *
 * @see SecondaryTable
 * @see Inheritance
 * @see OneToOne
 * @since Java Persistence 1.0
 */
@Target({ TYPE, METHOD, FIELD })
@Retention(RUNTIME)
public @interface PrimaryKeyJoinColumn {

	/**
	 * (Optional) The name of the primary key column of the current table.
	 * 
	 * Defaults to the same name as the primary key column of the primary
	 * table of the superclass (JOINED mapping strategy); the same
	 * name as the primary key column of the primary table
	 * (SecondaryTable mapping); or the same name as the
	 * primary key column for the table for the referencing entity
	 * (OneToOne mapping).
	 */
	String name() default "";

	/**
	 * (Optional) The name of the primary key column of the table
	 * being joined to.
	 * 

	 * Defaults to the same name as the primary key column of the primary table
	 * of the superclass (JOINED mapping strategy); the same name
	 * as the primary key column of the primary table
	 * (SecondaryTable mapping); or the same name as the
	 * primary key column for the table for the referencing entity
	 * (OneToOne mapping).
	 */
	String referencedColumnName() default "";

	/**
	 * (Optional) The SQL fragment that is used when generating the
	 * DDL for the column. This should not be specified for a
	 * OneToOne primary key association.
	 * 
	 * Defaults to the generated SQL to create a column of the inferred type.
	 */
	String columnDefinition() default "";
}