I'm using Tapestry 5.3.
In a Tapestry component, I'm trying to implement an event handler that creates responses to AJAX requests.
I know that I can call MarkupWriterFactory#newPartialMarkupWriter to get an instance of MarkupWriter and then generate the response using this instance. The built-in mixin Autocomplete generates responses to AJAX requests in this way. Here is a trivial example:
#Inject
private MarkupWriterFactory markupWriterFactory;
#OnEvent("myevent")
Object generatePartialMarkup() {
final ContentType contentType = new ContentType("text/html");
final MarkupWriter markupWriter = markupWriterFactory.newPartialMarkupWriter(contentType);
markupWriter.element("hr");
markupWriter.end();
return new TextStreamResponse(contentType.toString(), markupWriter.toString());
}
However, this is a clumsy solution for a partial HTML that is much more complex than just a hr element. I wonder if there is a chance to create such response using a Tapestry block rather than generating the response "manually" via MarkupWriter. If I just return an instance of block from the event handler, an exception is thrown when the event is triggered.
Thanks.
Looks like you're making life difficult for yourself. From what I can see you can solve this with an eventlink, a zone and an event handler which returns a Block. See here for more info.
Not entirely sure what you're doing but if you need to render a block as a string, see the capture component here
Related
I am new to Django but i am advanced programmer in other frameworks.
What i intend to do:
Press a form button, triggering Javascript that fires a Ajax request which is processed by a Django View (creates a file) that return plain simple JSON data (the name of the file) - and that is appended as a link to a DOM-Element named 'downloads'.
What i achieved so far instead:
Press the button, triggering js that fires a ajax request which is process by a Django view (creates a file) that return the whole page appended as a duplicate to the DOM-Element named 'downloads' (instead of simple JSON data).
here is the extracted code from the corresponding Django view:
context = {
'filename': filename
}
data['filename'] = render_to_string(current_app+'/json_download_link.html', context)
return HttpResponse(json.dumps(data), content_type="application/json")
I tried several variants (like https://stackoverflow.com/a/2428119/850547), with and without RequestContext object; different rendering strats.. i am out of ideas now..
It seems to me that there is NO possibility to make ajax requests without using a template in the response.. :-/ (but i hope i am wrong)
But even then: Why is Django return the main template (with full DOM) that i have NOT passed to the context...
I just want JSON data - not more!
I hope my problem is understandable... if you need more informations let me know and i will add them.
EDIT:
for the upcoming questions - json_download_link.html looks like this:
Download
But i don't even want to use that!
corresponding jquery:
$.post(url, form_data)
.done(function(result){
$('#downloads').append(' Download CSV')
})
I don't understand your question. Of course you can make an Ajax request without using a template. If you don't want to use a template, don't use a template. If you just want to return JSON, then do that.
Without having any details of what's going wrong, I would imagine that your Ajax request is not hitting the view you think it is, but is going to the original full-page view. Try adding some logging in the view to see what's going on.
There is no need to return the full template. You can return parts of template and render/append them at the frontend.
A template can be as small as you want. For example this is a template:
name.html
<p>My name is {{name}}</p>
You can return only this template with json.dumps() and append it on the front end.
What is your json_download_link.html?
assuming example.csv is string
data ={}
data['filename'] = u'example.csv'
return HttpResponse(simplejson.dumps(data), content_type="application/json")
Is this what you are looking for?
so still a newb to nodeJS and back end code in general. I need some help with ajax and node. For instance I have a function that goes like this
function random(response) {
var objToJson = {...};
response.write(objToJson);
response.end();
}
if instead of writing I want to pass this json object to another function as a response of an ajax call made to it how would that be?
Thanks for you help!
Node.js allows you to easy manipulate HTTP request and response objects.
Ajax still sends a HTTP request object and the Ajax onsuccess callback manipulates a HTTP response object.
Writing an object to a response for an ajax request allows your ajax success handler to manipulate that data.
There are abstraction libraries for RPC like now
It sounds like you want to return a javascript object to work with in your client-side code. While that's not possible directly (you can't send an object directly over HTTP; you're always serializing/deserialing in some fashion), you can certainly return a JSON payload and easily convert that to an in-memory javascript object. If that's what you're doing, you should set the response content type to application/json.
response.setHeader("Content-Type", "application/json");
If you're writing "pure" javascript (no framework wrapping XmlHttpRequest), you'll need to eval() the responseText to convert it to an object. If you're using something like jQuery, it will do that work for you (assuming you set the content type as suggested above).
$('submitbutton').addEvent( 'submit', function(e){
e.stop();
$('fuss').send();
req2.send();
});
trying to get this working but not sure if it is possible and had no success so far.
Mootools docs doesnt helped me either.
Will the multiple usage of .send() work?
Do i have to specify the data beeing send for the html request or does it take automatical the data beeing send by the form ?
It's in the documentation: http://mootools.net/docs/core/Request/Request#Element:send
This shorthand method will do a request using the post-processed data from all of the fields.
You can do as many requests in a specific event as you wish, as long as they're all asynchronous.
In your specific example it would seem you want to do two requests using two different methods, one with setting up a new Request class manually and the second doing it via the Element Method.
Based on your last comment, I wrote a little example in jsFiddle.
Basically I think you don't need two request for your goal. Just override onRequest method to update the html.
I need to be able to add some javascript to all ajax postback responses (PartialViewContext.isAjaxRequest == true) but I am not succeeding with any implementation I try.
I have tried implementing a
PhaseListener
and adding my script using PartialResponseWriter.insert* to add eval blocks, as well as trying to add the script by creating a script element. (Results in CDATA cannot nest, or just invalid XML)
I have tried decorating PartialViewContextFactory to override the
PartialViewContext.processPartial
and add the script after the wrapped instance has processed it...
How should I go about adding sripts to an Ajax response? Something similar to what .NET has with Scriptmanager.registerClientScriptBlock preferably.
Thank you
Use the javascript libraries that come bundled with your JSF2 implementation (as required by the spec). Here are the API docs:
http://java.sun.com/javaee/javaserverfaces/2.0/docs/js-api/index.html
The jsf.ajax.addOnEvent solves your problem of "adding some javascript to all ajax postback responses":
This function must accept a reference to an existing JavaScript function. The JavaScript function reference must be added to a list of callbacks, making it possible to register more than one callback by invoking jsf.ajax.addOnEvent more than once.
We are using the Dynamic Script Tag with JsonP mechanism to achieve cross-domain Ajax calls. The front end widget is very simple. It just calls a search web service, passing search criteria supplied by the user and receiving and dynamically rendering the results.
Note - For those that aren’t familiar with the Dynamic Script Tag with JsonP method of performing Ajax-like requests to a service that return Json formatted data, I can explain how to utilise it if you think it could be relevant to the problem.
The service is WCF hosted on IIS. It is Restful so the first thing we do when the user clicks search is to generate a Url containing the criteria. It looks like this...
https://.../service.svc?criteria=john+smith
We then use a dynamically created Html Script Tag with the source attribute set to the above Url to make the request to our service. The result is returned and we process it to show the results.
This all works fine, but we noticed that when using IE the service receives the request from the client Twice. I used Fiddler to monitor the traffic leaving the browser and sure enough I see two requests with the following urls...
Request 1: https://.../service.svc?criteria=john+smith
Request 2: https://.../service.svc?criteria=john+smith&_=123456789
The second request has been appended with some kind of Id. This Id is different for every request.
My immediate thought is it was something to do with caching. Adding a random number to the end of the url is one of the classic approaches to disabling browser caching. To prove this I adjusted the cache settings in IE.
I set “Check for newer versions of stored pages” to “Never” – This resulted in only one request being made every time. The one with the random number on the end.
I set this setting value back to the default of “Automatic” and the requests immediately began to be sent twice again.
Interestingly I don’t receive both requests on the client. I found this reference where someone is suggesting this could be a bug with IE. The fact that this doesn’t happen for me on Firefox supports this theory.
Can anyone confirm if this is a bug with IE? It could be by design.
Does anyone know of a way I can stop it happening?
Some of the more vague searches that my users will run take up enough processing resource to make doubling up anything a very bad idea. I really want to avoid this if at all possible :-)
I just wrote an article on how to avoid caching of ajax requests :-)
It basically involves adding the no cache headers to any ajax request that comes in
public abstract class MyWebApplication : HttpApplication
{
protected MyWebApplication()
{
this.BeginRequest += new EventHandler(MyWebApplication_BeginRequest);
}
void MyWebApplication_BeginRequest(object sender, EventArgs e)
{
string requestedWith = this.Request.Headers["x-requested-with"];
if (!string.IsNullOrEmpty(requestedWith) && requestedWith.Equals(”XMLHttpRequest”, StringComparison.InvariantCultureIgnoreCase))
{
this.Response.Expires = 0;
this.Response.ExpiresAbsolute = DateTime.Now.AddDays(-1);
this.Response.AddHeader(”pragma”, “no-cache”);
this.Response.AddHeader(”cache-control”, “private”);
this.Response.CacheControl = “no-cache”;
}
}
}
I eventually established the reason for the duplicate requests. As I said, the mechanism I chose to use for making Ajax calls was with Dynamic Script Tags. I build the request Url, created a new Script element and assigned the Url to the src property...
var script = document.createElement(“script”);
script.src = https://....”;
Then to execute the script by appending it to the Document Head. Crucially, I was using the JQuery append function...
$(“head”).append(script);
Inside the append function JQuery was anticipating that I was trying to make an Ajax call. If the type of element being appended is a Script, then it executes a special routine that makes an Ajax request using the XmlHttpRequest object. But the script was still being appended to the document head, and being executed there by the browser too. Hence the double request.
The first came direct from the script – the one I intended to happen.
The second came from inside the JQuery append function. This was the request suffixed with the randomly generated query string argument in the form “&_=123456789”.
I simplified things by preventing the JQuery library side effect. I used the native append function...
document.getElementByTagName(“head”).appendChild(script);
One request now happens in the way I intended. I had no idea that the JQuery append function could have such a significant side effect built in.
See www.enhanceie.com/redir/?id=httpperf for further discussion.