foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/annotations/MapKeyConvert.java

/*
 * Copyright (c) 1998, 2020 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:
//     01/28/2009-2.0 Guy Pelletier
//       - 248293: JPA 2.0 Element Collections (part 1)
//     03/27/2009-2.0 Guy Pelletier
//       - 241413: JPA 2.0 Add EclipseLink support for Map type attributes
package org.eclipse.persistence.annotations;

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

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

/**
 * The MapKeyConvert annotation specifies that a named converter should be used
 * with the corresponding mapped attribute key column. The MapKeyConvert
 * annotation has the following reserved names:
 *  - serialized: Will use a SerializedObjectConverter
 *  on the associated mapping. When using a SerializedObjectConverter the
 *  database representation is a binary field holding a serialized version of
 *  the object and the object-model representation is a the actual object
 *  - class-instance: Will use an ClassInstanceConverter
 *  on the associated mapping.  When using a ClassInstanceConverter the database
 *  representation is a String representing the Class name and the object-model
 *  representation is an instance of that class built with a no-args constructor
 *  - none - Will place no converter on the associated mapping. This can be used
 *  to override a situation where either another converter is defaulted or
 *  another converter is set.
 *
 *  When these reserved converters are not used, it is necessary to define a
 *  converter to use using the @Converter annotation.
 *
 * @see org.eclipse.persistence.annotations.Converter
 * @see org.eclipse.persistence.annotations.ObjectTypeConverter
 * @see org.eclipse.persistence.annotations.TypeConverter
 * @see org.eclipse.persistence.mappings.converters.SerializedObjectConverter
 * @see org.eclipse.persistence.mappings.converters.ClassInstanceConverter
 *
 * @author Guy Pelletier
 * @since EclipseLink 1.2
 */
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface MapKeyConvert {
    /**
     * (Optional) The name of the converter to be used.
     */
    String value() default "none";
}