How to return a JSON object in standard web forms .Net

Question

The objective is to call a method which does it\'s thing then returns a JSON object.

I\'m new to JSON.

I have a default.aspx and in it the following code. No

Answer 1

I would suggest an HttpHandler. No page lifecycle (so it is blazing fast) and much cleaner code-separation, as well as reusability.

Add a new item to your project of type "Generic Handler". This will create a new .ashx file. The main method of any class that implements IHttpHandler is ProcessRequest. So to use the code from your original question:

public void ProcessRequest (HttpContext context) {

    if(String.IsNullOrEmpty(context.Request["day"]))
    {
        context.Response.End(); 
    }

    string json = "";
    byte[] bytes = getByteArray();

    json = JsonConvert.SerializeObject(bytes);
    context.Response.ContentType = "text/json";
    context.Response.Write(json);
}

Change the url in your AJAX call and that should do it. The JavaScript would look like this , where GetFileHandler.ashx is the name of the IHttpHandler you just created:

$.ajax(
    {
        type: "POST",
        async: true,
        url: 'Handlers/GetFileHandler.ashx',
        data: "Day=" + $.toJSON(day),
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (msg) {
            console.log("SUCCESS:" + msg);
        },
        error: function (msg) {
            console.log("error:" + msg);
        }
    });

Another small point to consider, if you need access to the Session object from within the Handler code itself, make sure to inherit from the IRequiresSessionState interface:

public class GetFileHandler : IHttpHandler, IRequiresSessionState

Answer 2

Yes your method has to be static with the WebMethod attribute

Basic example:

CS

using System;
using System.Web.Services;

public partial class _Default : System.Web.UI.Page
{
  [WebMethod(EnableSession=false)]
  public static string HelloWorld()
  {
    return "Hello World";
  }
}

Javascript

<script>
    $.ajax({
      type: "POST",
      url: "Default.aspx/HelloWorld",
      data: "{}",
      contentType: "application/json",
      dataType: "json",
      success: function(msg) {
        console.log(msg.d);
      }
    });
</script>

Answer 3

Been a while since I worked with webforms, but if remember correctly it should work if you put the webmethod attribute over GetFile method and make that method static.

 [WebMethod]
 public static string GetFile(string day)

Furthermore, how you post data in ajax method is a bit off. Remove querystring day from url and data should be in json format, something like {"day":day}