How to return JSON from a 2.0 asmx web service

Question

I am using .Net framework 2.0 / jQuery to make an Ajax call to a 2.0 web service. No matter what I set the contentType to in the ajax call, the service always returns XML. I want it to return Json!

Here is the call:

      $(document).ready(function() {          $.ajax({             type: "POST",             url: "DonationsService.asmx/GetDate",             data: "{}",             contentType: "application/json; charset=utf-8",             dataType: "json",             success: function(msg) {               // Hide the fake progress indicator graphic.               $('#RSSContent').removeClass('loading');                // Insert the returned HTML into the <div>.               $('#RSSContent').html(msg.d);             }           });         });     

Here is what the request header looks like in Fiddler:

POST /DonationsService.asmx/GetDate HTTP/1.1 x-requested-with: XMLHttpRequest Accept-Language: en-us Referer: http://localhost:1238/text.htm Accept: application/json, text/javascript, */* Content-Type: application/json; charset=utf-8 Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; eMusic DLM/4; .NET CLR 2.0.50727) Host: localhost:1238 Content-Length: 2 Connection: Keep-Alive Pragma: no-cache 

I have tried setting the contentType to 'text/json' and get the same results.

Here is the web service method:

<WebMethod()> _ Public Function GetDate() As String      'just playing around with Newtonsoft.Json     Dim sb As New StringBuilder     Dim sw As New IO.StringWriter(sb)     Dim strOut As String = String.Empty      Using jw As New JsonTextWriter(sw)         With jw             .WriteStartObject()             .WritePropertyName("DateTime")             .WriteValue(DateTime.Now.ToString)             .WriteEndObject()         End With         strOut = sw.ToString     End Using      Return strOut  End Function 

and here is what it returns:

<?xml version="1.0" encoding="utf-8"?> <string xmlns="http://DMS.Webservices.org/">{"DateTime":"11/13/2008 6:04:22 PM"}</string> 

Does anyone know how to force the web service to return Json when I ask for Json?

Please don't tell me to upgrade to .Net Framework 3.5 or anything like that (I'm not that stupid). I need a 2.0 solution.

Answer 1

It's no problem to return JSON from ASMX services in ASP.NET 2.0. You just need the ASP.NET AJAX Extensions installed.

Do be sure to add the [ScriptService] decoration to your web service. That's what instructs the server side portion of the ASP.NET AJAX framework to return JSON for a properly formed request.

Also, you'll need to drop the ".d" from "msg.d" in my example, if you're using it with 2.0. The ".d" is a security feature that came with 3.5.