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Tapestry 5.3+ New Features : Part 2

10.03.2011
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AjaxResponseRender

This is one of the most useful feature of Tapestry 5.3. There is already a concept of Zone in Tapestry for Ajax but now it is complimented by AjaxResponseRenderer. This fills a lot of gaps at least for people coming from Wicket. It is a bit similar to AjaxRequestTarget but empowered with Zones and JSON. I have compiled a small example demonstrating most of the features.

Please Note : This is only a demonstration of how AjaxResponseRenderer is used. Obviously you should always prefer the ‘Zone way’ of doing things. Only when you need a combination of zone updates(multiple), small JavaScript callbacks and JSON callbacks, you can use this service. Also when you want to do different things(explained below) in different event handlers (may be belonging to different components), this service can be of great help.

 

@Import(library = "testJSON.js")
public class NewAjax {
    @Inject
    private AjaxResponseRenderer ajaxResponseRenderer;

    @InjectComponent
    private Zone topZone;

    @InjectComponent
    private Zone bottomZone;

    @Inject
    private JavaScriptSupport javaScriptSupport;

    @InjectComponent
    private EventLink jsonCallbackLink;

    @Inject
    private Messages messages;

    @AfterRender
    void addJavaScript(){
        javaScriptSupport.addInitializerCall("testJSON", jsonCallbackLink.getClientId());
    }

    @OnEvent("serverAlert")
    void showAlert() {
        ajaxResponseRenderer.addCallback(new JavaScriptCallback() {
            public void run(JavaScriptSupport javascriptSupport) {
                javascriptSupport.addScript(
                    String.format("alert('%s');", messages.get("server.hello")));
            }
        });
    }

    @OnEvent("sendJSON")
    void sendJSON() {
        ajaxResponseRenderer.addCallback(new JSONCallback() {
            public void run(JSONObject reply) {
                reply.put("message", messages.get("server.message"));
            }
        });
    }

    @OnEvent("multipleZoneUpdate")
    void showZones() {
        ajaxResponseRenderer.addRender("topZone", topZone).
            addRender("bottomZone", bottomZone);
    }

    public Date getDate() {
        return new Date();
    }

}
<html xmlns:t='http://tapestry.apache.org/schema/tapestry_5_1_0.xsd'>
    <head>
        <title>New Ajax Features</title>
    </head>

    <body>
        <div t:type='zone' t:id='topZone'>
             Zone ${date}
        </div>

        <a href='#' t:type='eventLink'
           t:event='multipleZoneUpdate' t:zone='topZone' t:id='multipleZoneLink'>
            Multiple Zone Update
        </a>

        <div t:type='zone' t:id='bottomZone'>
            Bottom Zone ${date}
        </div>

        <br/>

        <a t:type='eventLink' t:zone='topZone'
           t:id='javaScriptCallbackLink' t:event='serverAlert'>
            Show Feedback alert
        </a>

        <br/>

        <a t:type='eventLink' t:id='jsonCallbackLink' t:event='sendJSON'>
            Get alert message from server!
        </a>
    </body>

</html>
Tapestry.Initializer.testJSON = function(elementId){
    $(elementId).observe("click", function(event){

        Tapestry.ajaxRequest($(elementId).href, function(response){
            alert(response.responseJSON.message);
        });

        event.preventDefault();
    });
};
server.hello=Hello from Server!
server.message=Message from Server!!

For Multiple Zone Update

Instead of using MultiZoneUpdate, you can use AjaxRequestRenderer. The advantage is that it is now a service. You can call it from multiple event handlers present in different components handling the same event. Or imagine an event handler in a component which triggers another event that is handled by the container component. Now the component can add its internal zone and then trigger an event to which the container can respond by adding its own zone!!.

Using JavaScript callback

You can now do something on server-side and return an alert message !!

Using JSON callback

You can send a JSON response in addition to updating multiple zones !!

From http://tawus.wordpress.com/2011/10/01/tapestry-5-3-new-features-part-2/

Published at DZone with permission of Taha Siddiqi, author and DZone MVB.

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