/* * Copyright 2007 Amazon Technologies, Inc. or its affiliates. * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks * of Amazon Technologies, Inc. or its affiliates. All rights reserved. * * 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 com.amazon.carbonado; import java.lang.annotation.*; /** * Identifies a {@link Storable} property which is not directly persisted, but * is instead derived from other property values. A derived property cannot be * abstract, and a "set" method is optional. * *

Derived properties can be used just like a normal property in most * cases. They can be used in query filters, indexes, alternate keys, and they * can also be used to define a {@link Version} property. * *

If the derived property depends on {@link Join} properties and is also * used in an index or alternate key, dependencies must be listed in order for * the index to be properly updated. * *

Example:

 * @Indexes(@Index("uppercaseName"))
 * public abstract class UserInfo implements Storable<UserInfo> {
 *     /**
 *      * Derive an uppercase name for case-insensitive searches.
 *      */
 *     @Derived
 *     public String getUppercaseName() {
 *         String name = getName();
 *         return name == null ? null : name.toUpperCase();
 *     }
 *
 *     ...
 * }
 * 
* * @author Brian S O'Neill * @author Tobias Holgers * @since 1.2 */ @Documented @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) public @interface Derived { /** * List of properties that this property is derived from. */ String[] from() default {}; /** * Returns whether this property should be included when copying a * storable. Copying of a derived property uses the "get" and "set" methods * and requires the "set" method to be defined. Default false. */ boolean shouldCopy() default false; }