javax.persistence.DiscriminatorColumn Maven / Gradle / Ivy
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can obtain
* a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
* or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
* Sun designates this particular file as subject to the "Classpath" exception
* as provided by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the License
* Header, with the fields enclosed by brackets [] replaced by your own
* identifying information: "Portions Copyrighted [year]
* [name of copyright owner]"
*
* Contributor(s):
*
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
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;
import static javax.persistence.DiscriminatorType.STRING;
/**
* Is used to define the discriminator column for the
* {@link InheritanceType#SINGLE_TABLE SINGLE_TABLE} and
* {@link InheritanceType#JOINED JOINED} inheritance mapping strategies.
*
* The 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
*
*
If the DiscriminatorColumn annotation is missing,
* and a discriminator column is required, the name of the
* discriminator column defaults to "DTYPE" and the discriminator
* type to {@link DiscriminatorType#STRING DiscriminatorType.STRING}.
*
*
* Example:
* @Entity
* @Table(name="CUST")
* @Inheritance(strategy=SINGLE_TABLE)
* @DiscriminatorColumn(name="DISC", discriminatorType=STRING,length=20)
* public class Customer { ... }
*
* @Entity
* public class ValuedCustomer extends Customer { ... }
*
*
* @since Java Persistence 1.0
*/
@Target({TYPE})
@Retention(RUNTIME)
public @interface DiscriminatorColumn {
/**
* (Optional) The name of column to be used for the discriminator.
*/
String name() default "DTYPE";
/**
* (Optional) The type of object/column to use as a class discriminator.
* Defaults to {@link DiscriminatorType#STRING DiscriminatorType.STRING}.
*/
DiscriminatorType discriminatorType() default STRING;
/**
* (Optional) The SQL fragment that is used when generating the DDL
* for the discriminator column.
* Defaults to the provider-generated SQL to create a column
* of the specified discriminator type.
*/
String columnDefinition() default "";
/**
* (Optional) The column length for String-based discriminator types.
* Ignored for other discriminator types.
*/
int length() default 31;
}