jakarta.persistence.DiscriminatorValue Maven / Gradle / Ivy
/*
* Copyright (c) 2008, 2023 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:
// Linda DeMichiel - 2.1
// Linda DeMichiel - 2.0
package jakarta.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 the annotated
* entity type.
*
* The {@code DiscriminatorValue} annotation can only be specified
* on a concrete entity class.
*
*
If the {@code DiscriminatorValue} annotation is not specified,
* and a discriminator column is used, a provider-specific function
* is used to generate a value representing the entity type. If the
* {@link DiscriminatorType} is {@link DiscriminatorType#STRING
* STRING}, the discriminator value default is the entity name.
*
*
The inheritance strategy and the discriminator column are only
* specified for the root of an entity class hierarchy or subhierarchy
* in which a different inheritance strategy is applied. But the
* discriminator value, if not defaulted, should be specified for each
* concrete entity class in the hierarchy.
*
*
Example:
* {@snippet :
* @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 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 {@code DiscriminatorValue} annotation is not specified
* and a discriminator column is used, a provider-specific function
* is used to generate a value representing the entity type. If the
* {@link DiscriminatorType} is {@link DiscriminatorType#STRING
* STRING}, the discriminator value default is the entity name.
*/
String value();
}