How to get JSON response from a 3.5 asmx web service

Question

I have the following method:

using System.Web.Services;
using System.Web.Script.Services;
using System.Web.Script.Serialization;
using Newtonsoft.Json;
using System.Collections;

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
//[System.ComponentModel.ToolboxItem(false)]
[System.Web.Script.Services.ScriptService]

// [System.Web.Script.Services.ScriptService]
public class Tripadvisor : System.Web.Services.WebService {

    public Tripadvisor () {

        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }


    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public string HotelAvailability(string api)
    {
        JavaScriptSerializer js = new JavaScriptSerializer();
        string json = js.Serialize(api);
        //JsonConvert.SerializeObject(api);
        return json ;
    }

Here i set ResponseFormat attribute is json s still being returned as XML.

I want to json format using this asmx service Any ideas?

Answer 1

I faced the same issue, and included the below code to get it work.

[WebMethod]
[ScriptMethod(UseHttpGet=true ,ResponseFormat = ResponseFormat.Json)]
public void HelloWorld()
{
    Context.Response.Clear();
    Context.Response.ContentType = "application/json";
    Context.Response.Write("Hello World");
    //return "Hello World";
}

Update:

To get a pure json format, you can use javascript serializer like below.

public class WebService1 : System.Web.Services.WebService
{
    [WebMethod]
    [ScriptMethod(UseHttpGet=true ,ResponseFormat = ResponseFormat.Json)]
    public void HelloWorld()
    {
        JavaScriptSerializer js = new JavaScriptSerializer();
        Context.Response.Clear();
        Context.Response.ContentType = "application/json";           
        HelloWorldData data = new HelloWorldData();
        data.Message = "HelloWorld";
        Context.Response.Write(js.Serialize(data));


    }
}

public class HelloWorldData
{
   public String Message;
}

However this works for complex types, but string does not show any difference.