Calling simple web service (.asmx file) from AJAX and JQuery using JSON - parse error

Question

Making my first steps in trying to use all these technologies together.. I'm having some toubles..
Here is my Server side:

[WebMethod(EnableSession = true)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string simplestMethod()
{
  return "Simplest method returned";
}

And here is my client side:

 $(document).ready(function(){
   $("a").click(function(event){     
      $.ajax({
      type: "POST",
      url: "http://localhost:53346/d2/TAPI.asmx/simplestMethod",
      data: "{}",
      contentType: "application/json; charset=utf-8",
      dataType: "json",
      success: function (data) {
       alert(data.d);
      },
      error: function (XMLHttpRequest, textStatus, errorThrown) {
       alert("Error Occured!" +" | " + XMLHttpRequest +" | " + textStatus +" | " + 
       errorThrown );
      }
   });
  });
 });

The result is an alert that says:
Error Occured! | [object XMLHttpRequest] | parseerror | undefined.
What parsing failed and why?
I should mention that calling the WS method directly does work.
Thanks a lot!

What's the URL of the page? If it's running from a different host and/or port you won't get a response, as it'll be blocked by the same origin policy. — Nick Craver
– Nick Craver, Commented Sep 6, 2010 at 10:05

Community · Accepted Answer · 2017-05-23 12:24:28Z

4

Your code looks like good with one suspected place: url. You should replace url to something like "TAPI.asmx/simplestMethod" or "/d2/TAPI.asmx/simplestMethod".

Moreover if you want study to how to call web method with parameters or return more complex data from the web method look at How do I build a JSON object to send to an AJAX WebService? and asmx web service, json, javascript/jquery?, Can I return JSON from an .asmx Web Service if the ContentType is not JSON?. How to decode error messages from the exception inside of web method see Get xhr object in vb.net while ajax calling fails.

edited May 23, 2017 at 12:24

CommunityBot

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answered Sep 6, 2010 at 11:55

Oleg

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6 Comments

Oren A Over a year ago

No luck. changing the URL gives the same error, and when I change the error and success functions, I just get an alert that says "error". But thanks!

Oleg Over a year ago

@Oren A: You have textStatus=**parseerror**. So you should first of all show xhr.responseText with alert(xhr.responseText);

Oleg Over a year ago

@Oren A: By the way I tested your code. If work without any problem. So your real error is somewhere outside the code which you posted in your question.

Oren A Over a year ago

I've been reading.. Could it be that I should add something to the web.config? (I'm using .NET 4.0) What other places in the code are relevant? Thanks.

Oleg Over a year ago

@Oren A: To make you easy to compare your solution with one working I created a simple application in .NET 4.0 (Visual Studio 2010) which do the same what you describe in your question. You can download full code from ok-soft-gmbh.com/ForStackOverflow/SimpleWebService.zip

|

msn · Accepted Answer · 2011-09-01 10:36:10Z

2

when you want use WebMethod in jquery , you must add this tag to web.config

<configuration>
  <system.web>
    <httpModules>
      <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    </httpModules>
  </system.web>
</configuration>

good luck

answered Sep 1, 2011 at 10:36

msn

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