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.rest.arg;
018
019import static org.apache.juneau.common.utils.Utils.*;
020
021import org.apache.juneau.*;
022import org.apache.juneau.reflect.*;
023import org.apache.juneau.rest.*;
024import org.apache.juneau.rest.annotation.*;
025import org.apache.juneau.rest.httppart.*;
026
027/**
028 * Resolves method parameters and parameter types annotated with {@link Attr} on {@link RestOp}-annotated Java methods.
029 *
030 * <p>
031 * The parameter value is resolved using:
032 * <p class='bjava'>
033 *    <jv>opSession</jv>
034 *       .{@link RestOpSession#getRequest() getRequest}()
035 *       .{@link RestRequest#getAttributes() getAttributes}()
036 *       .{@link RequestAttributes#get(String) get}(<jv>name</jv>)
037 *       .{@link RequestAttribute#as(Class) as}(<jv>type</jv>);
038 * </p>
039 *
040 * <h5 class='section'>See Also:</h5><ul>
041 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JavaMethodParameters">Java Method Parameters</a>
042 * </ul>
043 */
044public class AttributeArg implements RestOpArg {
045
046   private final String name;
047   private final Class<?> type;
048
049   /**
050    * Static creator.
051    *
052    * @param paramInfo The Java method parameter being resolved.
053    * @return A new {@link AttributeArg}, or <jk>null</jk> if the parameter is not annotated with {@link Attr}.
054    */
055   public static AttributeArg create(ParamInfo paramInfo) {
056      if (paramInfo.hasAnnotation(Attr.class) || paramInfo.getParameterType().hasAnnotation(Attr.class))
057         return new AttributeArg(paramInfo);
058      return null;
059   }
060
061   /**
062    * Constructor.
063    *
064    * @param paramInfo The Java method parameter being resolved.
065    */
066   protected AttributeArg(ParamInfo paramInfo) {
067      this.name = getName(paramInfo);
068      this.type = paramInfo.getParameterType().inner();
069   }
070
071   private String getName(ParamInfo paramInfo) {
072      Value<String> n = Value.empty();
073      paramInfo.forEachAnnotation(Attr.class, x -> isNotEmpty(x.name()), x -> n.set(x.name()));
074      paramInfo.forEachAnnotation(Attr.class, x -> isNotEmpty(x.value()), x -> n.set(x.value()));
075      if (n.isEmpty())
076         throw new ArgException(paramInfo, "@Attr used without name or value");
077      return n.get();
078   }
079
080   @Override /* RestOpArg */
081   public Object resolve(RestOpSession opSession) throws Exception {
082      return opSession.getRequest().getAttribute(name).as(type).orElse(null);
083   }
084}