MVC5 Returning a Generic List of Objects via Jquery Ajax

Question

I am trying to retrieve a list of objects via jQuery Ajax

I have a controller Method like this:

[HttpGet]
public JsonResult GetAllStates(string listname = "")
{
     clsDdl ddl = new clsDdl();
     List<clsDdl> retval = new List<clsDdl>();
     ddl.id = "1";
     ddl.value = "Dropdown1";
     ddl.status = "DDL Status";
     ddl.attributes = "First Dropdown Text";
     retval.Add(ddl);

     //return retval;
     return Json(new
     {
         list = retval
     }, JsonRequestBehavior.AllowGet);
}

Heres my Dropdown class that I am trying to return

public class clsDdl
{
    public string id { get; set; }
    public string value { get; set; }
    public string status { get; set; }
    public string attributes { get; set; }
}

Code in my view looks like this

 function LoadListItems (options) {

 var listname = options.listname;

$.ajax({
         type: "GET",
         url: url,
         data: JSON.stringify({
             listname: listname
         }),
         contentType: "application/json; charset=utf-8",
         async: true,
         success: function (result) {
            alert(result[0].value);
         },
         error: function (xhr, status, err) {
           alert(err.toString(), 'Error - LoadListItemsHelper');
         }
       });

My controller action is being hit. But the alert is always 'Undefined'. I have also tried

 success: function (data) {
                 var result = data.d;
                 for (var i = 0; i < result.length; i++) {
                 alert(result[i].attributes);
                 }

No Success there either. What am I doing wrong ?

Thanks in advance...

Answer 1

1. You are returning JSON from the server. You have to set dataType in Ajax request to json

1. contentType --> Data sending to server

2. dataType --> data returned from Server

What is content-type and datatype in an AJAX request?

      $.ajax({
        type: "GET",
        url: url,
        data: JSON.stringify({  listname: listname }),
        contentType: "application/json; charset=utf-8",

//HERE
        dataType: 'json',
        success: function (result) {
              alert(result[0].value);
        },
        error: function (xhr, status, err) {
               alert(err.toString(), 'Error - LoadListItemsHelper');
        }
    });

2.

You are returning

return new Json(new {list = retval}, JsonRequestBehavior.AllowGet);

In success: function(result)

You can access the list like this: result.list[index]

success: function (result) {

      for(var i =0; i < result.list.length; i++){

         alert(result.list[i].value);
         alert(result.list[i].status);
      }
}

EDIT Based on Aivan Monceller 's comments you can do this:

As you are sending GET you don't need the

contentType: "application/json; charset=utf-8",

So you can write you Ajax like this:

      $.ajax({
        type: "GET",
        url: url,
        data: {  listname: listname },

//HERE
        dataType: 'json',
        success: function (result) {
              alert(result[0].value);
        },
        error: function (xhr, status, err) {
               alert(err.toString(), 'Error - LoadListItemsHelper');
        }
    });