001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.http.annotation;
018
019import static java.lang.annotation.ElementType.*;
020import static java.lang.annotation.RetentionPolicy.*;
021
022import java.lang.annotation.*;
023
024import org.apache.juneau.annotation.*;
025import org.apache.juneau.json.*;
026
027/**
028 * REST request body annotation.
029 *
030 * <p>
031 * Identifies a POJO to be used as the body of an HTTP request.
032 *
033 * <p>
034 * Can be used in the following locations:
035 * <ul>
036 *    <li>Arguments and argument-types of server-side <ja>@RestOp</ja>-annotated methods.
037 *    <li>Arguments and argument-types of client-side <ja>@RemoteOp</ja>-annotated interfaces.
038 *    <li>Methods and return types of server-side and client-side <ja>@Request</ja>-annotated interfaces.
039 * </ul>
040 *
041 * <h5 class='topic'>Arguments and argument-types of server-side @RestOp-annotated methods</h5>
042 *
043 * <p>
044 * On server-side REST, this annotation can be applied to method parameters or parameter classes to identify them as the body of an HTTP request.
045 *
046 * <h5 class='section'>Examples:</h5>
047 * <p class='bjava'>
048 *    <jc>// Used on parameter</jc>
049 *    <ja>@RestPost</ja>(<js>"/pets"</js>)
050 *    <jk>public void</jk> addPet(<ja>@Content</ja> Pet <jv>pet</jv>) {...}
051 * </p>
052 * <p class='bjava'>
053 *    <jc>// Used on class</jc>
054 *    <ja>@RestPost</ja>(<js>"/pets"</js>)
055 *    <jk>public void</jk> addPet(Pet <jv>pet</jv>) {...}
056 *
057 *    <ja>@Content</ja>
058 *    <jk>public class</jk> Pet {...}
059 * </p>
060 *
061 * <p>
062 * This is functionally equivalent to the following code...
063 * <p class='bjava'>
064 *    <ja>@RestPost</ja>(<js>"/pets"</js>)
065 *    <jk>public void</jk> addPet(RestRequest <jv>req</jv>) {
066 *       Pet <jv>pet</jv> = <jv>req</jv>.getContent().as(Pet.<jk>class</jk>);
067 *       ...
068 *    }
069 * </p>
070 *
071 * <h5 class='topic'>Arguments and argument-types of client-side @RemoteResource-annotated interfaces</h5>
072 *
073 * <h5 class='section'>See Also:</h5><ul>
074 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/Content">@Content</a>
075 * </ul>
076 *
077 * <h5 class='topic'>Methods and return types of server-side and client-side @Request-annotated interfaces</h5>
078 *
079 * <h5 class='section'>See Also:</h5><ul>
080 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/Request">@Request</a>
081 * </ul>
082 *
083 * <h5 class='section'>Notes:</h5><ul>
084 *    <li class='note'>
085 *       Annotation parameter values will be aggregated when used on POJO parent and child classes.
086 *       <br>Values on child classes override values on parent classes.
087 *    <li class='note'>
088 *       Annotation parameter values will be aggregated when used on both POJOs and REST methods.
089 *       <br>Values on methods override values on POJO classes.
090 *    <li class='warn'>
091 *       If using this annotation on a Spring bean, note that you are likely to encounter issues when using on parameterized
092 *       types such as <code>List&lt;MyBean&gt;</code>.  This is due to the fact that Spring uses CGLIB to recompile classes
093 *       at runtime, and CGLIB was written before generics were introduced into Java and is a virtually-unsupported library.
094 *       Therefore, parameterized types will often be stripped from class definitions and replaced with unparameterized types
095 *    (e.g. <code>List</code>).  Under these circumstances, you are likely to get <code>ClassCastExceptions</code>
096 *    when trying to access generalized <code>JsonMaps</code> as beans.  The best solution to this issue is to either
097 *    specify the parameter as a bean array (e.g. <code>MyBean[]</code>) or declare the method as final so that CGLIB
098 *    will not try to recompile it.
099 * </ul>
100 *
101 * <h5 class='section'>See Also:</h5><ul>
102
103 * </ul>
104 */
105@Documented
106@Target({PARAMETER,METHOD,TYPE})
107@Retention(RUNTIME)
108@Inherited
109@Repeatable(ContentAnnotation.Array.class)
110@ContextApply(ContentAnnotation.Applier.class)
111public @interface Content {
112
113    /**
114     * Optional description for the exposed API.
115     *
116     * @return The annotation value.
117     * @since 9.2.0
118     */
119    String[] description() default {};
120
121    /**
122    * Dynamically apply this annotation to the specified classes.
123    *
124    * <h5 class='section'>See Also:</h5><ul>
125    *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/DynamicallyAppliedAnnotations">Dynamically Applied Annotations</a>
126    * </ul>
127    *
128    * @return The annotation value.
129    */
130   String[] on() default {};
131
132   /**
133    * Dynamically apply this annotation to the specified classes.
134    *
135    * <p>
136    * Identical to {@link #on()} except allows you to specify class objects instead of a strings.
137    *
138    * <h5 class='section'>See Also:</h5><ul>
139    *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/DynamicallyAppliedAnnotations">Dynamically Applied Annotations</a>
140    * </ul>
141    *
142    * @return The annotation value.
143    */
144   Class<?>[] onClass() default {};
145
146   /**
147    * <mk>schema</mk> field of the <a class='doclink' href='https://swagger.io/specification/v2#parameterObject'>Swagger Parameter Object</a>.
148    *
149    * <p>
150    * The schema defining the type used for parameter.
151    *
152    * <p>
153    * This is a required attribute per the swagger definition.
154    * However, if not explicitly specified, the value will be auto-generated using {@link JsonSchemaSerializer}.
155    *
156    * <p>
157    * The {@link Schema @Schema} annotation can also be used standalone on the parameter or type.
158    * Values specified on this field override values specified on the type, and values specified on child types override values
159    * specified on parent types.
160    *
161    * <h5 class='section'>Used for:</h5>
162    * <ul class='spaced-list'>
163    *    <li>
164    *       Server-side schema-based parsing and parsing validation.
165    *    <li>
166    *       Server-side generated Swagger documentation.
167    *    <li>
168    *       Client-side schema-based serializing and serializing validation.
169    * </ul>
170    *
171    * @return The annotation value.
172    */
173   Schema schema() default @Schema;
174}