Question

I am finding many “solutions” to this seemingly common problem, but alas, none seem to work for me – of course. I have some jQuery code that is trying to post to an ASP.NET 3.5 web service. The web service is supposed to return some json. I am getting 501 Internal Server errors with the code below, but according to the solutions found online, this is how it is supposed to be! The error function in the jquery code displays a parsererror. If I change how the data parameters are passed to the service ("userID=3456"), and remove the contentType property and change the dataType to “text”, then no errors, but it returns the JSON in an XML string.

Here is my jQuery code:

$.ajax({
        type: "POST",
        url: "mywebservice.asmx/Initialize",
        data: "{'userID': '3456'}",
        dataType: "json",
        contentType: "application/json; charset=utf-8",
        success: function(result) {
            alert("success");
        },
        error: function(request, status, errorThrown) {
            alert(status);
            alert(errorThrown);
        }
});

Here is my ASP.NET code:

<WebMethod()> _
Public Function Initialize(ByVal userID As Integer) As String
    Dim scormInstance As New CMI(userID)
    Return scormInstance.ToJsonString
End Function

Here are the HTTP request and response through my browser (Firefox 3.5.1)

http://localhost/cognition/webservices/cognitionapi.asmx/Initialize

POST /cognition/webservices/cognitionapi.asmx/Initialize HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 3.5.30729)
Accept: application/json, text/javascript, */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Content-Type: application/json; charset=utf-8
X-Requested-With: XMLHttpRequest
Referer: http://localhost/cognition/scorm-test2.html
Content-Length: 20
Cookie: RadEditorGlobalSerializeCookie=[_ctl0__ctl0__ctl0_Content_mainContent_mainContent_txtSpecialInstructionsModules]-[]#[_ctl0__ctl0__ctl0_Content_mainContent_mainContent_txtSpecialInstructionsToolbars]-[]#
Pragma: no-cache
Cache-Control: no-cache
{"userID":"1234"}

HTTP/1.x 500 Internal Server Error
Cache-Control: private
Content-Length: 4956
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/7.0
X-AspNet-Version: 2.0.50727
X-Powered-By: ASP.NET
Date: Mon, 27 Jul 2009 21:24:41 GMT

Any ideas as to what exactly I am doing wrong????!!!!???

Thanks!

Answer 1

After looking at some code i have that’s working i found this decoration on the function:

[WebMethod(), ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = false)]

also the postdata im passing in is in Json format, ie:

var postdata = "{'variable':'value'}";