org.eclipse.persistence.annotations.Transformation Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction 346465e
There is a newer version: 5.0.0-B03
/*******************************************************************************
 * 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:
 *     Andrei Ilitchev (Oracle), March 7, 2008 
 *        - New file introduced for bug 211300.  
 ******************************************************************************/  
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;

import javax.persistence.FetchType;

import static javax.persistence.FetchType.EAGER;

/**
 * Transformation is an optional annotation for org.eclipse.persistence.mappings.TransformationMapping.
 * TransformationMapping allows to map an attribute to one or more database columns.
 * 
 * Transformation annotation is an optional part of TransformationMapping definition.
 * Unless the TransformationMapping is write-only, it should have a ReadTransformer,
 * it defines transformation of database column(s) value(s)into attribute value.
 * Also unless it's a read-only mapping, either WriteTransformer annotation or WriteTransformers annotation
 * should be specified. Each WriteTransformer defines transformation of the attribute value to a single
 * database column value (column is specified in the WriteTransformer). 
 * 
 * @see org.eclipse.persistence.annotations.ReadTransformer
 * @see org.eclipse.persistence.annotations.WriteTransformer
 * @see org.eclipse.persistence.annotations.WriteTransformers
 * 
 * Transformation can be specified within an Entity, MappedSuperclass 
 * and Embeddable class.
 * 
 * @author Andrei Ilitchev
 * @since EclipseLink 1.0 
 */ 
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface Transformation {
    /**
     * (Optional) Defines whether the value of the field or property should
     * be lazily loaded or must be eagerly fetched. The EAGER strategy is a 
     * requirement on the persistence provider runtime that the value must be 
     * eagerly fetched. The LAZY strategy is a hint to the persistence provider 
     * runtime. If not specified, defaults to EAGER.
     */
    FetchType fetch() default EAGER;
    
    /**
     * (Optional) The optional element is a hint as to whether the value
     *  of the field or property may be null. It is disregarded
     *  for primitive types, which are considered non-optional.
     */
    boolean optional() default true;
}