javax.persistence.DiscriminatorValue Maven / Gradle / Ivy
// $Id: DiscriminatorValue.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.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Specifies the value of the discriminator column for
* entities of the given type.
*
* The DiscriminatorValue
* annotation can only be specified on a concrete entity
* class.
*
*
If the DiscriminatorValue annotation is not
* specified and a discriminator column is used, a provider-specific
* function will be used to generate a value representing the
* entity type. If the {@link DiscriminatorType} is
* STRING, the discriminator value
* default is the entity name.
*
*
The inheritance strategy and the discriminator column
* are only specified in the root of an entity class hierarchy
* or subhierarchy in which a different inheritance strategy is
* applied. The discriminator value, if not defaulted, should be
* specified for each entity class in the hierarchy.
*
*
*
* Example:
*
* @Entity
* @Table(name="CUST")
* @Inheritance(strategy=SINGLE_TABLE)
* @DiscriminatorColumn(name="DISC", discriminatorType=STRING, length=20)
* @DiscriminatorValue("CUSTOMER")
* public class Customer { ... }
*
* @Entity
* @DiscriminatorValue("VCUSTOMER")
* public class ValuedCustomer extends Customer { ... }
*
*
* @see DiscriminatorColumn
*
* @since Java Persistence 1.0
*/
@Target({TYPE})
@Retention(RUNTIME)
public @interface DiscriminatorValue {
/**
* (Optional) The value that indicates that the
* row is an entity of the annotated entity type.
*
* If the DiscriminatorValue annotation is not
* specified and a discriminator column is used, a
* provider-specific function will be used to generate a value
* representing the entity type. If the DiscriminatorType is
* STRING, the discriminator value default is the
* entity name.
*/
String value();
}