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 !!
Tagged: ajax, javascript, tapestry
Of course, your examples make things look more complicated than usually are in practice; in general, if you want to send back JSON from an Ajax request, just return the JSON object; if you want to update a single Zone, just return the block or component for its new content.
AjaxResponseRenderer is for when you want to render your components & blocks to update multiple client-side Zones, and do a few other tricky things. Still great to see the coverage.
Hi Howard
It is just a demonstration of the usage of AjaxResponseRenderer. I have added a note to avoid confusion
I was trying to only comprehend the usage of AjaxResponseRenderer but this post !..man I really learned a lot more. Thank you !
“Obviously you should always prefer the ‘Zone way’ of doing things.”
why? I have never liked the ‘Zone way’, it is very limiting. In my experience it is a rare case that I need to update a single zone, so I always end up using MultiZoneUpdate (5.1/2) or AjaxResponseRenderer (5.3).
The concept of zone is spread across the tapestry-core components & mixins. Yes it has limitations but it is very easy to use and extend. AjaxResponseRenderer for me is more of a Wicket’s AjaxResponseRequest (or something like that, who remembers
) but with the support of @Inject. You can use zone as an interface for your components and users can extend it using AjaxResponseRenderer in case they need to add more zones or custom scripts.
Could you help me?
I have problem with your example:
java.lang.IllegalStateException
Page must be specified before initializing for partial page render.
Filter stack frames Stack trace
org.apache.tapestry5.internal.services.PageRenderQueueImpl.partialRenderInitialized(PageRenderQueueImpl.java:100)
org.apache.tapestry5.internal.services.PageRenderQueueImpl.addPartialMarkupRendererFilter(PageRenderQueueImpl.java:131)
org.apache.tapestry5.internal.services.ajax.AjaxResponseRendererImpl.addFilter(AjaxResponseRendererImpl.java:96)
org.apache.tapestry5.internal.services.ajax.AjaxResponseRendererImpl.addCallback(AjaxResponseRendererImpl.java:105)
com.radiumone.post.portal.ui.app.pages.NewAjax.sendJSON(NewAjax.java:55)
com.radiumone.post.portal.ui.app.pages.NewAjax.dispatchComponentEvent(NewAjax.java)
“Only when you need a combination of zone updates(multiple), small JavaScript callbacks and JSON callbacks, you can use this service.”
What should I use If I need not small JavaScript callbacks.
Thanks.