ASP.NET MVC JsonResult return 500

Question

Hi

I have this controller method:

public JsonResult List(int number)
{
            var list = new Dictionary<int, string>();

            list.Add(1, "one");
            list.Add(2, "two");
            list.Add(3, "three"); 

            var q = (from h in list
                     where h.Key == number
                 select new
                 {
                     key = h.Key,
                     value = h.Value
                 });

            return Json(list);
}

On the client side, have this jQuery script:

$("#radio1").click(function () {
        $.ajax({
            url: "/Home/List",
            dataType: "json",
            data: { number: '1' },
            success: function (data) { alert(data) },
            error: function (xhr) { alert(xhr.status) }
        });
    });

I always get an error code 500. What's the problem?

Thank you

Answer 1

If you saw the actual response, it would probably say

This request has been blocked because sensitive information could be disclosed to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.

You'll need to use the overloaded Json constructor to include a JsonRequestBehavior of JsonRequestBehavior.AllowGet such as:

return Json(list, JsonRequestBehavior.AllowGet);

Here's how it looks in your example code (note this also changes your ints to strings or else you'd get another error).

public JsonResult List(int number) {
  var list = new Dictionary<string, string>();

  list.Add("1", "one");
  list.Add("2", "two");
  list.Add("3", "three");

  var q = (from h in list
           where h.Key == number.ToString()
           select new {
             key = h.Key,
             value = h.Value
           });

  return Json(list, JsonRequestBehavior.AllowGet);
}