using JQuery .ajax, a Success method is not called when using jquery 'json' vs 'text'

Question

I have an ASP.Net web page attempting to retrieve data from an asmx webservice using the jquery .axax method. The ajax method correctly call a success method when the dataType = "text", however I cannot get it to return when using the dataType of "json". Can anyone see what I am missing? I am getting the 'json' example online at http://weblogs.asp.net/jaredroberts/archive/2009/08/28/great-article-on-cascading-dropdown-list-and-jquery.aspx

Client:

function getText() {
    alert("getText");
    $.ajax({ 
        type: "POST", 
        url: "test.asmx/HelloWorld", 
        dataType: "text", 
        success: function(response) { alert("text"); }
    });
}

function getJson() {
    alert("getJson");
    $.ajax({ type: "POST", 
        url: "test.asmx/HelloWorld", 
        contentType: "application/json; charset=utf-8", 
        dataType: "json",
        success: function(response) { alert("json"); }
    });
}

Serverside Webservice Call:

[WebMethod]
public string HelloWorld() {
    return "Hello World";
}

You need to json encode that "hello world".

aziz punjani
– aziz punjani

2011-09-20 20:49:47 +00:00
Commented Sep 20, 2011 at 20:49 — aziz punjani
– aziz punjani, Commented Sep 20, 2011 at 20:49

davewilliams459 · Accepted Answer · 2011-09-21 17:20:23Z

2

In the end the source of my issue was the lack of the [ScriptService] attribute on the class decoration. I changed to class declartion to:

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
public class SearchFilters : System.Web.Services.WebService {
    [WebMethod]
    public string HelloWorld() {
        return "";
    }
}

Using Fiddler I discovered the following error message was returned:

Only Web services with a [ScriptService] attribute on the class definition can be called from script

answered Sep 21, 2011 at 17:20

davewilliams459

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Comments

cheeken · Accepted Answer · 2011-09-20 21:27:12Z

1

Your call fails because when you declare the datatype as json, jQuery is expecting JSON as a result, but you return Hello World. Try the code below, instead, to print "Hello World", which is valid JSON.

public string HelloWorld() {
    return """Hello World""";
}

edited Sep 20, 2011 at 21:27

answered Sep 20, 2011 at 20:52

cheeken

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2 Comments

cheeken Over a year ago

Sorry - I don't know VB at all and assumed it supported escape functionality it doesn't. I have amended my answer.

davewilliams459 Over a year ago

Actually this is c#, however the above still did not work. Thanks though!

Dmitry Samuylov · Accepted Answer · 2011-09-21 18:24:51Z

1

Here is what I tried and it worked perfectly:

Client:

<script type="text/javascript">
    $(function () {
        $('#testbutton').click(function () {
            $.ajax({
                type: "POST",
                url: "WebService1.asmx/HelloWorld",
                cache: false,
                contentType: "application/json; charset=utf-8",
                data: "{}",
                dataType: "json",
                success: function (data, status) {
                    var response = $.parseJSON(data.d);
                    alert(response.message);
                    alert(status);
                },
                error: function (xmlRequest) {
                    alert(xmlRequest.status + ' \n\r ' + xmlRequest.statusText + '\n\r' + xmlRequest.responseText);
                }
            });            
        });
    });
</script>

Serverside Webservice Call:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

namespace WebApplication2
{
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]    
    [System.Web.Script.Services.ScriptService]
    public class WebService1 : System.Web.Services.WebService
    {    
        [WebMethod]
        public string HelloWorld()
        {
            return "{ \"message\":\"Hello World\" }";
        }
    }
}

Make sure you have [System.Web.Script.Services.ScriptService] attribute on your webservice class.

NOTE: in the example above the returned JSON is hardcoded, but you can just as easily serialize the objects you want to return as JSON as follows for a hypothetical person object:

Person p = new Person();
p.FirstName = "Bob";
p.LastName = "Smith";
p.Age = 33;
p.Married = true;

Microsoft.Web.Script.Serialization.JavaScriptSerializer jss = new Microsoft.Web.Script.Serialization.JavaScriptSerializer();
string serializedPerson = jss.Serialize(p);

edited Sep 21, 2011 at 18:24

answered Sep 20, 2011 at 20:53

Dmitry Samuylov

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6 Comments

davewilliams459 Over a year ago

I am afraid this did not work, and as I am at a bank, I am not able to load FF. However I realy want to accomplish what the above article is doing, so why is this not working: public List<Cases> GetCases() { List<Cases> cases = new List<Cases>() { new Cases() { CaseName = "test" } }; return cases.ToList(); }

davewilliams459 Over a year ago

(sorry for the formatting) In the above example I am calling the 'GetCases' webmethod via 'json' (and 'text') using a jquery call to GetCases. GetCases returns List<OneCase>. However like above, 'text' returns a result, but the 'json' 'success' method never fires. Am I mssing something from the listed MS article?

Dmitry Samuylov Over a year ago

@davewilliams459 You need to see what the response from your service is. You can use Google Chrome, it has similar tools to Firebug, or install Fiddler for Internet Explorer and profile your ajax requests using that. But first of all, definitely see what is being sent and what is coming back in order to debug this further.

davewilliams459 Over a year ago

Grrrrr... Chrome, FireFox and Fiddler are restricted here at the bank. I'll have to figure out something. Grrrrr

Dmitry Samuylov Over a year ago

@davewilliams459 If you are doing web development involving ajax, at least one of those tools is essential to be productive. When i get to work, I'll try creating your solution from scratch and see if it works, i'll send/post a working copy for you.

|

Raj · Accepted Answer · 2013-04-23 18:41:24Z

0

Your class must be with attribute : [ScriptService] Then declare method:

  [WebMethod]
    public string GetSomeString()
    {
        return "SomeString";
    }

When you are trying to handle call:

function ShowString() {
        $.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "/YourService.asmx/GetSomeString" ,
            data: "{}",
            dataType: "json",
            success: function (msg) {
                console.debug(msg);
                alert(msg.d);
            }
        });

Will give you proper output what you are expecting "SomeString".

-Raj

answered Apr 23, 2013 at 18:41

Raj

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