Question

I have a webmethod hosted on domain A inside a .aspx page. I need to call this method from domain B. I am using $getJSON() to make this call, but when it comes back data.query.results[0] is always null.

Jquery code in domain B.

// Accepts a url and a callback function to run.
function requestCrossDomain() {
    var site = 'http://domain A/Services/A.aspx/GetString'; 
    var yql = 'http://query.yahooapis.com/v1/public/yql?q=' + encodeURIComponent('select * from html where url="' + site + '"') + '&format=json&callback=?';

    $.getJSON(yql, cbFunc);

    function cbFunc(data) {
        if (data.query.results[0]) {
            var result = JSON.parse(data.results[0]);
            alert(result);
        }
        else 
            throw new Error('Nothing returned from getJSON.');
    }
}

Domain A Webmethod

<WebMethod()> 
<ScriptMethod(ResponseFormat:=ResponseFormat.Json, UseHttpGet:=True)>
Public Shared Function GetString() As String
    Dim ResultString As String = New JavaScriptSerializer().Serialize("Test Result")
    Return ResultString
End Function

The above method works absolutely fine when I call the method from the same domain. But cross domain call always returns null.

When I checked in Fiddler, there is track that says the server responded and the content length is 616. But the result I get back is null.

Response Headers

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Encoding: gzip
Vary: Accept-Encoding
Server: Microsoft-IIS/7.5
X-AspNet-Version: 4.0.30319
X-SourceFiles: =?UTF-8?B?QzpcQ29tbW9uXFBST1xIUk9cU2VydmljZXNcSFJPQ29yZS5hc3B4?=
X-Powered-By: ASP.NET
Date: Mon, 05 Dec 2011 15:07:54 GMT
Content-Length: 616

I am not sure what I am missing. I’ve tried using JSONP and $getJSON. Both doesn’t return any value.

Please let me know if you require any further information.

Answer 1

ok, I see two problems with the script. First, you should create the cbFunc before passing it into the getJSON. Secondly lets check if yahoo is returning it’s data by alerting when it was created. If the results is empty you’ll need help with the yahoo api more.

// Accepts a url and a callback function to run.
function requestCrossDomain() {
    function cbFunc(data) {
        if (data.query.created) {
            //var result = JSON.parse(data.results[0]);
            alert(data.query.created);//put a breakpoint here to check the data.results if you get it created.
        }
        else 
            throw new Error('Nothing returned from getJSON.');
    }

    var site = 'http://domain A/Services/A.aspx/GetString'; 
    var yql = 'http://query.yahooapis.com/v1/public/yql?q=' + encodeURIComponent('select * from html where url="' + site + '"') + '&format=json&callback=?';

    $.getJSON(yql, cbFunc);

}