    001// Copyright 2007-2013 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 java.io.IOException;
    018
    019import org.apache.tapestry5.TrackableComponentEventCallback;
    020import org.apache.tapestry5.internal.InternalConstants;
    021import org.apache.tapestry5.internal.structure.ComponentPageElement;
    022import org.apache.tapestry5.internal.structure.Page;
    023import org.apache.tapestry5.internal.util.Holder;
    024import org.apache.tapestry5.ioc.internal.util.TapestryException;
    025import org.apache.tapestry5.json.JSONObject;
    026import org.apache.tapestry5.services.Ajax;
    027import org.apache.tapestry5.services.ComponentEventRequestHandler;
    028import org.apache.tapestry5.services.ComponentEventRequestParameters;
    029import org.apache.tapestry5.services.ComponentEventResultProcessor;
    030import org.apache.tapestry5.services.Environment;
    031import org.apache.tapestry5.services.Request;
    032
    033/**
    034 * Similar to {@link ComponentEventRequestHandlerImpl}, but built around the Ajax request cycle, where the action
    035 * request sends back an immediate JSON response containing the new content.
    036 */
    037@SuppressWarnings({"unchecked", "rawtypes"})
    038public class AjaxComponentEventRequestHandler implements ComponentEventRequestHandler
    039{
    040    private final RequestPageCache cache;
    041
    042    private final Request request;
    043
    044    private final PageRenderQueue queue;
    045
    046    private final ComponentEventResultProcessor resultProcessor;
    047
    048    private final Environment environment;
    049
    050    private final AjaxPartialResponseRenderer partialRenderer;
    051
    052    private final PageActivator pageActivator;
    053
    054    public AjaxComponentEventRequestHandler(RequestPageCache cache, Request request, PageRenderQueue queue, @Ajax
    055    ComponentEventResultProcessor resultProcessor, PageActivator pageActivator,
    056                                            Environment environment,
    057                                            AjaxPartialResponseRenderer partialRenderer)
    058    {
    059        this.cache = cache;
    060        this.queue = queue;
    061        this.resultProcessor = resultProcessor;
    062        this.pageActivator = pageActivator;
    063        this.request = request;
    064        this.environment = environment;
    065        this.partialRenderer = partialRenderer;
    066    }
    067
    068    public void handle(ComponentEventRequestParameters parameters) throws IOException
    069    {
    070        Page activePage = cache.get(parameters.getActivePageName());
    071
    072        final Holder<Boolean> resultProcessorInvoked = Holder.create();
    073        resultProcessorInvoked.put(false);
    074
    075        ComponentEventResultProcessor interceptor = new ComponentEventResultProcessor()
    076        {
    077            public void processResultValue(Object value) throws IOException
    078            {
    079                resultProcessorInvoked.put(true);
    080
    081                resultProcessor.processResultValue(value);
    082            }
    083        };
    084
    085        // If we end up doing a partial render, the page render queue service needs to know the
    086        // page that will be rendered (for logging purposes, if nothing else).
    087
    088        queue.setRenderingPage(activePage);
    089
    090        request.setAttribute(InternalConstants.PAGE_NAME_ATTRIBUTE_NAME, parameters.getActivePageName());
    091
    092        if (pageActivator.activatePage(activePage.getRootElement().getComponentResources(), parameters
    093                .getPageActivationContext(), interceptor))
    094            return;
    095
    096        Page containerPage = cache.get(parameters.getContainingPageName());
    097
    098        ComponentPageElement element = containerPage.getComponentElementByNestedId(parameters.getNestedComponentId());
    099
    100        // In many cases, the triggered element is a Form that needs to be able to
    101        // pass its event handler return values to the correct result processor.
    102        // This is certainly the case for forms.
    103
    104        TrackableComponentEventCallback callback = new ComponentResultProcessorWrapper(interceptor);
    105
    106        environment.push(ComponentEventResultProcessor.class, interceptor);
    107        environment.push(TrackableComponentEventCallback.class, callback);
    108
    109        boolean handled = element
    110                .triggerContextEvent(parameters.getEventType(), parameters.getEventContext(), callback);
    111
    112        if (!handled)
    113            throw new TapestryException(String.format("Request event '%s' (on component %s) was not handled; you must provide a matching event handler method in the component or in one of its containers.", parameters.getEventType(), element.getCompleteId()), element,
    114                    null);
    115
    116        environment.pop(TrackableComponentEventCallback.class);
    117        environment.pop(ComponentEventResultProcessor.class);
    118
    119
    120        // If the result processor was passed a value, then it will already have rendered. Otherwise it was not passed a value,
    121        // but it's still possible that we still want to do a partial page render ... if filters were added to the render queue.
    122        // In that event, run the partial page render now and return.
    123
    124        boolean wasInvoked = resultProcessorInvoked.get();
    125
    126        if ((!wasInvoked) && queue.isPartialRenderInitialized())
    127        {
    128            partialRenderer.renderPartialPageMarkup();
    129            return;
    130        }
    131
    132        // If the result processor was passed a value, then it will already have rendered, and there is nothing more to do.
    133
    134        if (wasInvoked) { return; }
    135
    136        // Send an empty JSON reply if no value was returned from the component event handler method.
    137        // This is the typical behavior when an Ajax component event handler returns null. It still
    138        // will go through a pipeline that will add information related to partial page rendering.
    139
    140        resultProcessor.processResultValue(new JSONObject());
    141    }
    142}