Monorail cannot read JSON (a list of objects) data received from jQuery

Question

I have the following jquery ajax:

 $(".gridster ul").gridster({
               widget_margins: [5, 5],
               widget_base_dimensions: [280, 280],
               draggable: {
                stop: function(event, ui){ 
                              var orderState = {
        photos:  $(".gridster ul").data("gridster").serialize(),
        promoid: $.getUrlVar('promoId')
        };
       $.ajax({
                url: "/Photos/SetOrder",
                data: {neworder:orderState},
                dataType: 'json',
                type: 'POST'
            });

Which I send to a Monorail 2.1 controller.

The orderState object from JS looks likes this:

neworder[photos][0][height]=1
neworder[photos][0][id]=98315
neworder[photos][0][width]=1
neworder[photos][0][x]=2
neworder[photos][0][y]=1
neworder[photos][1][height]=1
neworder[photos][1][id]=98316
neworder[photos][1][width]=1
neworder[photos][1][x]=1
neworder[photos][1][y]=1
neworder[photos][2][height]=1
neworder[photos][2][id]=98317
neworder[photos][2][width]=1
neworder[photos][2][x]=1
neworder[photos][2][y]=2
neworder[photos][3][height]=1
neworder[photos][3][id]=98318
neworder[photos][3][width]=1
neworder[photos][3][x]=1
neworder[photos][3][y]=3
neworder[promoid]=163844

And it should map to the following c# viewmodel class:

 public class OrderViewModel
    {
        public int height { get; set; }

        public int width { get; set; }

        public int x { get; set; }

        public int y { get; set; }

        public int id { get; set; }
    }

    public class NewPromoImageOrderViewModel
    {
        public NewPromoImageOrderViewModel()
        {
            Photos = new List<OrderViewModel>();
        }

        public int PromoId { get; set; }

        public List<OrderViewModel> Photos { get; set; }
    }

Used by the following action:

  [return: JSONReturnBinder]
        [AccessibleThrough(Verb.Post)]
        public object SetOrder([JSONBinder("neworder")] NewPromoImageOrderViewModel neworder)
        {
            //bla
        }

And the response it gives me is this:

Message: Error building method arguments. Last param analyzed was neworder with value ''

StackTrace: at Castle.MonoRail.Framework.SmartDispatcherController.BuildMethodArguments(ParameterInfo[] parameters, IRequest request, IDictionary2 actionArgs) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\SmartDispatcherController.cs:line 329 at Castle.MonoRail.Framework.SmartDispatcherController.InvokeMethod(MethodInfo method, IRequest request, IDictionary2 extraArgs) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\SmartDispatcherController.cs:line 80 at Castle.MonoRail.Framework.ActionMethodExecutorCompatible.Execute(IEngineContext engineContext, IController controller, IControllerContext context) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\ActionMethodExecutor.cs:line 79 at Castle.MonoRail.Framework.Controller.RunActionAndRenderView() in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\Controller.cs:line 1639

Inner exception: ArgumentNullException

Message: Value cannot be null. Parameter name: s

StackTrace: at System.IO.StringReader..ctor(String s) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type) at Castle.MonoRail.Framework.Services.NewtonsoftJSONSerializer.Deserialize(String jsonString, Type expectedType) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\Services\NewtonsoftJSONSerializer.cs:line 100 at Castle.MonoRail.Framework.JSONBinderAttribute.Bind(IEngineContext context, IController controller, IControllerContext controllerContext, ParameterInfo parameterInfo) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\Attributes\JSONBinderAttribute.cs:line 135 at Castle.MonoRail.Framework.SmartDispatcherController.BuildMethodArguments(ParameterInfo[] parameters, IRequest request, IDictionary`2 actionArgs) in C:\Dropbox\Projects\Monorail\castleproject-MonoRail-98c93ac\castleproject-MonoRail-98c93ac\MR2\src\Castle.MonoRail.Framework\SmartDispatcherController.cs:line 288

I'm pretty sure my mappings and viewmodel class are correct. JQuery does send the expected json object, but Monorail seems to have problems converting it. Could this be a bug?

EDIT:Well, Monorail wasn't at fault at here... The things i put through the post WERENT A JSON after all. After using this library: https://code.google.com/p/jquery-json/, I managed to convert the object to JSON. I thought that by choosing the dataType:"json" would have been enough, but apparently it's not.

Answer 1

The datatype option in the $.ajax call refers to the data that is expected. What you need to do is this:

$.ajax({
  url: "/Photos/SetOrder",  
  contentType: 'application/json; charset=utf-8',
  data: JSON.stringify({neworder:orderState}),
  type: 'POST'
});