I have a view that I'm binding with knockoutjs. I need to add data dynamically to a list in the viewmodel using ajax post. 

```
            var data = {
                model: ko.toJS(self.Model),
                name: name
            }

             $.ajax({
                url: options.url + "AddAdvantage",
                type: 'POST',
                dataType: 'json',
                contentType: 'application/json',
                data: JSON.stringify(data),
                traditional: true,
                success: function (data) {
                    self.UpdateOnChange = false;
                    ko.mapping.fromJS(data, self.Model);
                    self.UpdateOnChange = true;
                }
            });

```

when the data parameter is passed to the controller action:

```
[HttpPost]
public JsonResult AddAdvantage([ModelBinder(typeof(AdvantageModelBinder))] AdvantageViewModel model, string name) {
}

```

name value is passed, but model is always null

I have tried this:

```
            var data = {
                model: ko.toJSON(self.Model),
                name: name
            }

```

also tried:

```
            var data = JSON.stringify({
                model: ko.toJSON(self.Model),
                name: name
            });

```

same result. 

this works fine:

```
           $.ajax({
                url: options.url + "AddAdvantage",
                type: 'POST',
                dataType: 'json',
                contentType: 'application/json',
                data: ko.toJSON(self.Model),
                traditional: true,
                success: function (data) {
                    self.UpdateOnChange = false;
                    ko.mapping.fromJS(data, self.Model);
                    self.UpdateOnChange = true;
                }
            });

```

My ModelBinder

```
public class AdvantageModelBinder: DefaultModelBinder
{
    public AdvantageModelBinder()
    {
    }

    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        ValueProviderResult value = bindingContext.ValueProvider.GetValue("WizardType");
        Type typeByTypeName = AdvantageModelBinder.GetTypeByTypeName((string)value.ConvertTo(typeof(string)));
        object obj = Activator.CreateInstance(typeByTypeName);
        bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => obj, typeByTypeName);
        return obj;
    }

    public static Type GetTypeByTypeName(string typeName)
    {
        Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
        for (int i = 0; i < (int)assemblies.Length; i++)
        {
            Type type = assemblies[i].GetType(typeName, false, true);
            if (type != null)
            {
                return type;
            }
        }
        throw new ArgumentException("Can't find the specified type in the loaded assemblies.", typeName);
    }
}

```

can anyone tell how to fix this?