XMLHttpRequest used in XPCOM - problem

[gemme]

Hello

I want to download some data in my XPCOM component. I made this code:

Code: Select all

for (var el in this.ObservedSites)
{
   var Request =
      Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
      .createInstance(Components.interfaces.nsIXMLHttpRequest);
   
   Request.open("GET", this.ObservedSites[el].URL, true);
   Request.el = el;
   Request.onload = this.siteChecked;
   Request.send(null);
}

I set Request.el to identify responses (as in http://kb.mozillazine.org/XMLHttpReques ... nous_calls - adding custom data to XMLHttpRequest object).

But I've got this error:
Cannot modify properties of a WrappedNative = NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN
on the line:

Code: Select all

Request.el = el;

Is there any way to make this asynchronous and to identify (in the onload event) requests?

[doron]

var myThis = this;
var func = function(){myThis.siteChecked('unique identifier')};
Request.onload = func;

[gemme]

The line

Code: Select all

Request.onload = func;

still causes the "Cannot modify properties of a WrappedNative = NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN" error

EDIT: Adding

Code: Select all

Request instanceof Components.interfaces.nsIJSXMLHttpRequest;

helped.

This thread was helpful: http://www.mail-archive.com/dev-tech-xp ... 00264.html

[gemme]

Argh, it still doesn't work correctly.

The code is

Code: Select all

for (var el in this.ObservedSites)
{
   (...)
   var Notify = this;
   var func =
      function(event)
      {
         Notify.siteChecked(event, el);
      };
   Request.onload = func;
   (...)
}

But when there are 2 items in this.ObservedSites, Notify.siteChecked is called twice, with the same el value.
I don't understand it ...

[gemme]

This code hopefully works, if it can help anyone in the future:

Code: Select all

var Notify = this;
var func =
   eval(
      "function(event) \
      { \
         Notify.siteChecked(event, " + el + "); \
      };"
      );
Request.onload = func;

[ashishpatil]

Hey you forgot your code and use this one.

function(url, callback)
{
var request = Components.classes['@mozilla.org/xmlextras/xmlhttprequest;1']
.getService(Components.interfaces.nsIXMLHttpRequest);

var this_ = this;

if (callback)
{
request = request.QueryInterface(Components.interfaces.nsIDOMEventTarget);
request.callback = callback;
request.addEventListener("load",
function (event) {
this_.SendAsyncDone(event);
},
true);
}
try {
request.open("GET", url, true);
request.setRequestHeader("User-Agent" , userAgent);
request.send(null);
}
catch(e)
{

}
},

asyncDone: function(event)
{
var request = event.target;

if (request.readyState != 4)
return;

var callback = request.callback;
callback(request.responseText);
if (request.status == 200)
request.done = true;
}
its woking fine for me, let me know if you helped with it.