jQuery 1.5 AJAX call fails with “invalid label” for JSON requests

问题

I've just upgraded from version 1.4 to version 1.5 of jQuery, and now my AJAX calls always fail with the "invalid label" error.

An example request is:

jQuery.ajax({
    async: false
    , dataType: "json"
    , error: function (xhr, status, error) { ... }
    , success: function (data, status, xhr) { ... }
    , type: "post"
    , url: "ajax/request.asp"
});

On the net I found this error is raised when the returned JSON is not wrapped with jQuery's callback (e.g. jQuery1234({ "something": "abcd" }).

The problem is I'm returning a JSON, not a JSONP (and I state it in the AJAX request), so why I must specify a callback in the returned JSON?

The 1.5 changelog says nothing about this... (Or it's me who can't read?)

Update:

This is an example of a not working JSON:

{
   "esito":"Ok",
   "centriCosto":[
      {
         "id":"1",
         "descrizione":"Colazione"
      },
      {
         "id":"2",
         "descrizione":"Pranzo"
      },
      {
         "id":"3",
         "descrizione":"Cena"
      }
   ]
}

And this is the same callback-wrapped working JSON:

jQuery1502710949228847014_1296739130498({
   "esito":"Ok",
   "centriCosto":[
      {
         "id":"1",
         "descrizione":"Colazione"
      },
      {
         "id":"2",
         "descrizione":"Pranzo"
      },
      {
         "id":"3",
         "descrizione":"Cena"
      }
   ]
})

By the way, Firebug says both of them are valid JSONs (and he's very picky about correctness).

回答1:

Ok, I found out what the hell is happening.

jQuery's Validation plug-in is not compatible with jQuery 1.5 (see one and two), removing the plug-in yields to the right behaviour.

If someone else has this problem, there's a patch in the plug-in's repository: link

回答2:

I actually ran into similar problem but it appears to be related to this bug: http://bugs.jquery.com/ticket/8398

It is not necessarily related to jQuery-validate and it took me a while to figure things out. It turns out that jQuery 1.5 is modifying subsequent ajax calls for json to jsonp which leads to this error.

I fixed it by following one of the workarounds suggested in the bug change history and placing the following code somewhere before my ajax calls are made:

$.ajaxSetup({
   jsonp: null,
   jsonpCallback: null
});

Should fix any problems for other ajax requests too.

回答3:

Here is a possible workaround for those with the validator plugin.

dataType: "text json"

Works like a charm. Don't ask me why. On chrome, you can see a jquery syntax error parsing the ":" on the json return. And make no mistake about it, the return is valid json. I didn't try it but I suspect Tom's answer above will also work.

回答4:

try: Did a quick search for json in jquery-1.5.js and found this on row 6905:

// Detect, normalize options and install callbacks for jsonp requests

jQuery.ajaxPrefilter("json jsonp", function( s, originalSettings, dataIsString /* internal */ ) {

removing the "json" from first argument will add correct behavior when spec. dataType:"json"

回答5:

If your server-side code is relying on the callback name beginning with "jsonp", you may have a problem. The callback name prefix was changed to "jQuery" in version 1.5.

回答6:

looks like this is fixed now in v1.6 - had the same issue after upgrading to ver 1.5.1 & after upgrading to 1.6 the issue disappeared.

回答7:

Updating to jquery 1.7 solves it

回答8:

Here's the solution:

$.post("...", {},
        function(data) {

      // dont forget to add below lines         

         },"json");

来源：https://stackoverflow.com/questions/4886525/jquery-1-5-ajax-call-fails-with-invalid-label-for-json-requests

标签

json

jquery

jquery-1.5