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

/*******************************************************************************
 * Copyright (c) 1998, 2013 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 v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * 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";
}