001 // Copyright 2007, 2008, 2010 The Apache Software Foundation
002 //
003 // Licensed under the Apache License, Version 2.0 (the "License");
004 // you may not use this file except in compliance with the License.
005 // You may obtain a copy of the License at
006 //
007 // http://www.apache.org/licenses/LICENSE-2.0
008 //
009 // Unless required by applicable law or agreed to in writing, software
010 // distributed under the License is distributed on an "AS IS" BASIS,
011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012 // See the License for the specific language governing permissions and
013 // limitations under the License.
014
015 package org.apache.tapestry5.internal.services;
016
017 import org.apache.tapestry5.ContentType;
018 import org.apache.tapestry5.TrackableComponentEventCallback;
019 import org.apache.tapestry5.internal.InternalConstants;
020 import org.apache.tapestry5.internal.structure.ComponentPageElement;
021 import org.apache.tapestry5.internal.structure.Page;
022 import org.apache.tapestry5.internal.util.Holder;
023 import org.apache.tapestry5.ioc.internal.util.TapestryException;
024 import org.apache.tapestry5.json.JSONObject;
025 import org.apache.tapestry5.services.*;
026
027 import java.io.IOException;
028
029 /**
030 * Similar to {@link ComponentEventRequestHandlerImpl}, but built around the Ajax request cycle, where the action
031 * request sends back an immediate JSON response containing the new content.
032 */
033 @SuppressWarnings("unchecked")
034 public class AjaxComponentEventRequestHandler implements ComponentEventRequestHandler
035 {
036 private final RequestPageCache cache;
037
038 private final Request request;
039
040 private final PageRenderQueue queue;
041
042 private final ComponentEventResultProcessor resultProcessor;
043
044 private final PageContentTypeAnalyzer pageContentTypeAnalyzer;
045
046 private final Environment environment;
047
048 private final AjaxPartialResponseRenderer partialRenderer;
049
050 private final PageActivator pageActivator;
051
052 public AjaxComponentEventRequestHandler(RequestPageCache cache, Request request, PageRenderQueue queue, @Ajax
053 ComponentEventResultProcessor resultProcessor, PageActivator pageActivator,
054 PageContentTypeAnalyzer pageContentTypeAnalyzer, Environment environment,
055 AjaxPartialResponseRenderer partialRenderer)
056 {
057 this.cache = cache;
058 this.queue = queue;
059 this.resultProcessor = resultProcessor;
060 this.pageActivator = pageActivator;
061 this.pageContentTypeAnalyzer = pageContentTypeAnalyzer;
062 this.request = request;
063 this.environment = environment;
064 this.partialRenderer = partialRenderer;
065 }
066
067 public void handle(ComponentEventRequestParameters parameters) throws IOException
068 {
069 Page activePage = cache.get(parameters.getActivePageName());
070
071 final Holder<Boolean> resultProcessorInvoked = Holder.create();
072 resultProcessorInvoked.put(false);
073
074 ComponentEventResultProcessor interceptor = new ComponentEventResultProcessor()
075 {
076 public void processResultValue(Object value) throws IOException
077 {
078 resultProcessorInvoked.put(true);
079
080 resultProcessor.processResultValue(value);
081 }
082 };
083
084 // If we end up doing a partial render, the page render queue service needs to know the
085 // page that will be rendered (for logging purposes, if nothing else).
086
087 queue.setRenderingPage(activePage);
088
089 if (pageActivator.activatePage(activePage.getRootElement().getComponentResources(), parameters
090 .getPageActivationContext(), interceptor))
091 return;
092
093 ContentType contentType = pageContentTypeAnalyzer.findContentType(activePage);
094
095 request.setAttribute(InternalConstants.CONTENT_TYPE_ATTRIBUTE_NAME, contentType);
096
097 Page containerPage = cache.get(parameters.getContainingPageName());
098
099 ComponentPageElement element = containerPage.getComponentElementByNestedId(parameters.getNestedComponentId());
100
101 // In many cases, the triggered element is a Form that needs to be able to
102 // pass its event handler return values to the correct result processor.
103 // This is certainly the case for forms.
104
105 TrackableComponentEventCallback callback = new ComponentResultProcessorWrapper(interceptor);
106
107 environment.push(ComponentEventResultProcessor.class, interceptor);
108 environment.push(TrackableComponentEventCallback.class, callback);
109
110 boolean handled = element
111 .triggerContextEvent(parameters.getEventType(), parameters.getEventContext(), callback);
112
113 if (!handled)
114 throw new TapestryException(ServicesMessages.eventNotHandled(element, parameters.getEventType()), element,
115 null);
116
117 environment.pop(TrackableComponentEventCallback.class);
118 environment.pop(ComponentEventResultProcessor.class);
119
120
121 // If the result processor was passed a value, then it will already have rendered. Otherwise it was not passed a value,
122 // but it's still possible that we still want to do a partial page render ... if filters were added to the render queue.
123 // In that event, run the partial page render now and return.
124
125 boolean wasInvoked = resultProcessorInvoked.get();
126
127 if ((!wasInvoked) && queue.isPartialRenderInitialized())
128 {
129 partialRenderer.renderPartialPageMarkup();
130 return;
131 }
132
133 // If the result processor was passed a value, then it will already have rendered, and there is nothing more to do.
134
135 if (wasInvoked) { return; }
136
137 // Send an empty JSON reply if no value was returned from the component event handler method.
138 // This is the typical behavior when an Ajax component event handler returns null.
139
140 JSONObject reply = new JSONObject();
141
142 resultProcessor.processResultValue(reply);
143 }
144 }