JSON response returning null when local webservice called

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Hello everyone,

I have made a simple webservice in asp.net, my service.asmx file contains webmethod as :

C#

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void HelloWorld() {
      JavaScriptSerializer serializer = new JavaScriptSerializer();
        string jsonData = serializer.Serialize("Hello World");
        Context.Response.ContentType = "application/json; charset=utf-8";
        Context.Response.Write(jsonData);
        //return jsonData;
}

This webservice returns me output of "Hello World"

Now i have hosted this webservice on IIS and accessing this webservice from localhost also works very fine.

Now i have created one website in asp.net in which there is a button which invokes this webservice through AJAX and JSON

The code is :

      function invokeService() {

          $.ajax({
              url: "http://localhost/SampleService/Service.asmx/HelloWorld",
              type: "POST",
              contentType: "application/json; charset=utf-8",
              dataType: "json",
              success: function (msg) {
                  alert(msg);
              },
              error: function () {
                  alert("this error");
              }
          });
          return false;
      }
<input type="button" id="btnInvokeService" value="Invoke Service" onclick ="invokeService();" />

Now the invokeService method is called of jSON but the output i am returning is "null" value..

I have also tried to change webservice webmethod with returning string value but the end result is same.

Please help me how can i achieve output in JSON alert as Hello world.. Please help me

Thanking you in advance.

Krunal

Posted 21-Mar-14 3:49am

krunalpanchalN

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Richard C Bishop · Answer 1 · 2014-03-21T04:19:00

Solution 1

I would recommend changing your AJAX call URL to this:

url: "Service.asmx/HelloWorld",

The reference to the local host would not bode well when published to IIS.

[EDIT]

Change your service to this:

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string HelloWorld() {
      JavaScriptSerializer serializer = new JavaScriptSerializer();
        string jsonData = serializer.Serialize("Hello World");
        Context.Response.ContentType = "application/json; charset=utf-8";
        Context.Response.Write(jsonData);
        return jsonData;
}

Posted 21-Mar-14 4:19am

Richard C Bishop

Updated 21-Mar-14 5:18am

v2

Comments

krunalpanchalN 21-Mar-14 10:22am

Hi Richard,

Now it tells 'this error' it means it is going to error function..Please help

Richard C Bishop 21-Mar-14 10:28am

What is "this error"?

krunalpanchalN 21-Mar-14 10:25am

I have also tried SampleService/Service.asmx/HelloWorld, but still says 'this error'

krunalpanchalN 21-Mar-14 10:29am

It is just simple alert message if it reaches in error function....it means that there is some error... i have also checked the error status and it is "500" but the webservice is working very fine...

Richard C Bishop 21-Mar-14 10:41am

Change the error function to this:
error: function (jqXHR){
alert(jqXHR.responseText);
}

This will tell you what the actual error is.

krunalpanchalN 21-Mar-14 10:48am

It says No webservice found..but the webservice is present on localhost..

ANd if i type url : "http://localhost/SampleService/Service.asmx/HelloWorld".. it doesnt return any error instead it goes inside success function but returns null as output.

Please suggest

Richard C Bishop 21-Mar-14 11:15am

I just figured it out I think. You can keep your URL as you have it, but your HelloWorld() method does not return anything. Therefore, you would get null as the value in your AJAX response. You need to return a string value and change the method signature to do so.

krunalpanchalN 21-Mar-14 11:20am

I tried same thing...but still shows null

now my webmethod looks like :

public string HelloWorld() {
JavaScriptSerializer serializer = new JavaScriptSerializer();
string jsonData = serializer.Serialize("Hello World");
Context.Response.ContentType = "application/json; charset=utf-8";
//Context.Response.Write(jsonData);
return jsonData;
}

and the url in JSON looks like : http://localhost/SampleService/Service.asmx/HelloWorld

Still facing same problem..

Please help

Richard C Bishop 21-Mar-14 11:26am

Put a break-point at the instantiation and jsonData. See if the value you are assigning it is actually "Hello World" or if it is getting null.

krunalpanchalN 21-Mar-14 11:39am

I am executing the webservice and it is showing me output as "Hello World"...but it is not getting the same at JSON...

Richard C Bishop 21-Mar-14 11:43am

Try in your success function:
alert(msg.d)

krunalpanchalN 21-Mar-14 11:57am

Tried same thing.. but doesnt shows any alert.. i mean alert(msg.d) doesnt gives any alert..