Question

So on a change of one drop down list I’m trying to populate a second list.

I have this client side function:

 $('#ProjectReference').change(function() {

       var url = "@Url.Action("GetProjectIterations", "Rally")";
       var data = { selectedProject: $('#ProjectReference').val() };


       $.getJSON(url, data, function(iterations) {
              alert("hello?");
              var items;
              $.each(iterations, function(i, iteration) {
                   items += "<option value='" + iteration.Name + "'>" + iteration.Name + "</option>";
              });
            }
       );

       $.ajax({
            url: url,
            type: 'GET',
            dataType: 'json',
            data: data,
            contentType: 'application/json; charset=utf-8',
            success: function (iterations) {
                        alert("hello?");
                        var items;
                        $.each(iterations, function(i, iteration) {
                            items += "<option value='" + iteration.Name + "'>" + iteration.Name + "</option>";
                        });

                        $("#ProjectIteration").html(items);},
             failure: function () { alert("nope");}
            });
        });

I’ve tried 2 different formats for calling my controller (so I know I don’t need both – I’ve just included both to highlight what I’ve tried).

My controller gets called, I am returning data but none of my alerts get fired (and nothing happens to the drop down list I am trying to update). So maybe the way I’m returning my data isn’t correct? My select list has a count of 33 so it appears to have data before its returned.

public ActionResult GetProjectIterations(string selectedProject)
{
     var projectIterations = cache.Get("ProjectIterations") as Hashtable;
     var iterations = (projectIterations[selectedProject] as ArrayList).Cast<DynamicJsonObject>().ToList();
     var selectList = iterations.Select(
            iteration => new SelectListItem {Text = iteration["Name"], Value = iteration["Name"]});
     return Json(selectList);
}

Answer 1

Since you’re using GET you need to be changing the JsonRequestBehavior on your controller action.

In your example, the code should be:

public ActionResult GetProjectIterations(string selectedProject)
{
     var projectIterations = cache.Get("ProjectIterations") as Hashtable;
     var iterations = (projectIterations[selectedProject] as ArrayList).Cast<DynamicJsonObject>().ToList();
     var selectList = iterations.Select(
            iteration => new SelectListItem {Text = iteration["Name"], Value = iteration["Name"]});
     return Json(selectList, JsonRequestBehavior.AllowGet); //check the overload for Json()
}