How to use ajax json data by using jquery in mvc 4?

Question

How to use $.post or $.getJSON to get json from mvc controlller but not working below? Would you like help me?

    var controlRole = function () {

    var  _url = 'IsStudent/';
    console.log('IsStudent');
   $.post(_url, {}, function (data) {
       console.log('IsStudent2');
       if (data == "true") {
           $('#btnSent_').hide();
           $('#btnDraft_').hide();
           $('#btn_Inbox_').show();
           $('#btnTrash_').show();
            $.post('FillProgramListByUser/', {}, function (result) {
                console.log('IsStudent3');
                console.log(result);
                $("#liProgramContainer ul").append('<li ><a class="btn" href="javascript:;"  data-title="Sent">'+result.Name+'</a><b></b></li>');
            });


           // $.getJSON("FillProgramListByUser/", user, updateFields);


        }
       else {
           $('#btnSent_').show();
           $('#btnDraft_').show();
           $('#btn_Inbox_').show();
           $('#btnTrash_').show();

        }
    });
}

Controller side:

        public JsonResult FillProgramListByUser()
    {
        string UserName =  SessionVariables.CurrentUser.UserName;
        int OrganizationId = SessionVariables.CurrentUser.OrganizationId;
        IList<Program> programs = new List<Program>();
        if (UserName != "system_admin")
        {
            programs = Uow.Programs.GetAll().Where(q => q.OrganizationId == OrganizationId).ToList();
        }


        return Json(programs, "application/json", Encoding.UTF8, JsonRequestBehavior.AllowGet);
    }

    [HttpPost]
    public string IsStudent()
    {
        string UserName = SessionVariables.CurrentUser.UserName;

        if (UserName != "system_admin")
        {
            return  "true";
        }
        else
        {
            return "false";
        }

    }

Answer 1

Your controller action should return a JsonResult and not some strings:

[HttpPost]
public ActionResult IsStudent()
{
    string UserName = SessionVariables.CurrentUser.UserName;

    if (UserName != "system_admin")
    {
        return Json(new { success = true });
    }

    return Json(new { success = false });
}

Also in your FillProgramListByUser action you don't need to be explicitly setting the content type response header nor the encoding:

public ActionResult FillProgramListByUser()
{
    string UserName =  SessionVariables.CurrentUser.UserName;
    int OrganizationId = SessionVariables.CurrentUser.OrganizationId;
    IList<Program> programs = new List<Program>();
    if (UserName != "system_admin")
    {
        programs = Uow.Programs.GetAll().Where(q => q.OrganizationId == OrganizationId).ToList();
    }

    return Json(programs, JsonRequestBehavior.AllowGet);
}

Also adapt your script so that the urls are not hardcoded as in your example but you used URL helpers to generate them:

<script type="text/javascript">
    var controlRole = function () {
        var isStudentUrl = '@Url.Action("IsStudent")';
        $.post(isStudentUrl, function (data) {
           if (data.success) {
               $('#btnSent_').hide();
               $('#btnDraft_').hide();
               $('#btn_Inbox_').show();
               $('#btnTrash_').show();
               var fillProgramListByUserUrl = '@Url.Action("FillProgramListByUser")';
               $.post(fillProgramListByUserUrl, function (result) {
                   $("#liProgramContainer ul").append('<li><a class="btn" href="javascript:;"  data-title="Sent">'+result.Name+'</a><b></b></li>');
               });
           } else {
               $('#btnSent_').show();
               $('#btnDraft_').show();
               $('#btn_Inbox_').show();
               $('#btnTrash_').show();
            }
        });
    };
</script>

Next put breakpoints in your controller actions and see if they are hit. Also don't forget to look at the network tab of your javascript debugging tool (FireBug or Chrome Developer Toolbar) which is where you will see the exact AJAX request being sent to the server and what does the server respond to. You will see the HTTP status code returned and you could also see the contents of the response. If the status code is non 2xx the success callback of your AJAX request will not be executed.

Another thing you should check is the Program model which is being returned by your FillProgramListByUser controller action. In there you are attempting to JSON serialize an IList<Program> but be careful: if this Program class has some circular references (often happens if you don't use view models but are directly passing your EF domain models to the views) you won't be able to JSON serialize it. The answer is of course obvious: use a view model.