I'm using the Razor HtmlHelper for the ComboBox populating the items on-demand and filtered much like your cascading combobox demo (http://demos.telerik.com/aspnet-mvc/combobox/cascadingcombobox
). However my combobox needs to pass multiple filters to the server in a specific JSON object (filters must form part of an array) and data is returned in a JSON object. In summary I really need to have complete control of the request and response handling and would like to know the approach you'd recommend. Would a custom datasource be best with a parameterMap? I've not seen a real in-depth demo of how this is done with the Razor HtmlHelpers.