    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.corelib.mixins;
    014
    015import org.apache.tapestry5.*;
    016import org.apache.tapestry5.annotations.AfterRender;
    017import org.apache.tapestry5.annotations.Events;
    018import org.apache.tapestry5.annotations.InjectContainer;
    019import org.apache.tapestry5.annotations.Parameter;
    020import org.apache.tapestry5.corelib.components.Zone;
    021import org.apache.tapestry5.internal.util.CaptureResultCallback;
    022import org.apache.tapestry5.ioc.annotations.Inject;
    023import org.apache.tapestry5.services.javascript.JavaScriptSupport;
    024
    025/**
    026 *
    027 * This mixin periodically refreshs a {@link org.apache.tapestry5.corelib.components.Zone zone}
    028 * by triggering an event on the server using ajax requests.
    029 *
    030 *
    031 * Server-side, the mixin triggers the "refresh" event with the mixin's context. A container may but
    032 * does not need to handle the event. If the event is handled and a value is returned, that value is
    033 * used to render the response. Otherwise, the Zone's body is re-rendered.
    034 *
    035 * <b>Note: </b> This mixin is only meant for a {@link org.apache.tapestry5.corelib.components.Zone zone}.
    036 *
    037 * @tapestrydoc
    038 */
    039@Events(EventConstants.REFRESH)
    040public class ZoneRefresh
    041{
    042    /**
    043     * Period between two consecutive refreshes (in seconds). If a new refresh occurs before the
    044     * previous refresh has completed, it will be skipped.
    045     */
    046    @Parameter(required = true, defaultPrefix = BindingConstants.LITERAL)
    047    private int period;
    048
    049    /**
    050     * Context passed to the event
    051     */
    052    @Parameter
    053    private Object[] context;
    054
    055    @InjectContainer
    056    private Zone zone;
    057
    058    @Inject
    059    private JavaScriptSupport javaScriptSupport;
    060
    061    @Inject
    062    private ComponentResources resources;
    063
    064    //For testing purpose
    065    ZoneRefresh(Object[] context, ComponentResources resources, JavaScriptSupport javaScriptSupport, Zone zone)
    066    {
    067        this.context = context;
    068        this.resources = resources;
    069        this.javaScriptSupport = javaScriptSupport;
    070        this.zone = zone;
    071    }
    072
    073    @AfterRender
    074    void addJavaScript()
    075    {
    076        Link link = resources.createEventLink("zoneRefresh", context);
    077
    078        javaScriptSupport.require("t5/core/zone-refresh").with(zone.getClientId(), period, link.toString());
    079    }
    080
    081    Object onZoneRefresh(EventContext eventContext)
    082    {
    083        CaptureResultCallback<Object> callback = new CaptureResultCallback<Object>();
    084        resources.triggerContextEvent(EventConstants.REFRESH, eventContext, callback);
    085
    086        if (callback.getResult() != null)
    087        {
    088            return callback.getResult();
    089        }
    090
    091        return zone.getBody();
    092    }
    093
    094}