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
015package org.apache.tapestry5.internal.services;
016
017import org.apache.tapestry5.ContentType;
018import org.apache.tapestry5.TrackableComponentEventCallback;
019import org.apache.tapestry5.internal.InternalConstants;
020import org.apache.tapestry5.internal.structure.ComponentPageElement;
021import org.apache.tapestry5.internal.structure.Page;
022import org.apache.tapestry5.internal.util.Holder;
023import org.apache.tapestry5.ioc.internal.util.TapestryException;
024import org.apache.tapestry5.json.JSONObject;
025import org.apache.tapestry5.services.*;
026
027import 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")
034public 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}