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/*
 * Copyright 2010 Bull S.A.S.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.persistence;

import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.DiscriminatorType.STRING;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * The DiscriminatorColumn annotation can be specified on an entity class
 * (including on an abstract entity class).

 * 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 STRING.
 * @see JPA 2.0 specification
 * @author Florent Benoit
 * @since JPA 1.0 version.
 */
@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.
     */
    DiscriminatorType discriminatorType() default STRING;

    /**
     * (Optional) The SQL fragment that is used when generating the DDL for the
     * discriminator column.
     */
    String columnDefinition() default "";

    /**
     * (Optional) The column length for String-based discriminator types.
     * Ignored for other discriminator types.
     */
    int length() default 31;
}