title: Kendo DropdownList server filtering with added parameters
body: <p>I'm happy if I can get the filtering working client or serverside, but combining sending parameters on the DataSource action and ServerFiltering(true) results in an null filter value (text parameter). </p>
  
  <p>The dropdownlist is part of a series which uses cascading.</p>
  
  <p>View:</p>
  
  <pre><code>@(Html.Kendo().DropDownList()
            .Name("name")
            .OptionLabel(new SelectListItem { Text = "Select...", Value = "" })
            .DataTextField("Text")
            .DataValueField("Value")
            .Filter("contains")
            .DataSource(source =&gt;
            {
                source.Read(read =&gt;
                {
                    read.Action("Action", "Controller")
                        .Data("params");
                })
                .ServerFiltering(true);
            })
            .Enable(false)
            .AutoBind(false)
            .CascadeFrom("parent")
      )
  
      &lt;script&gt;
          function params() {
              return {
                  a: '',
                  b: 1
              };
          }
      &lt;/script&gt;
  </code></pre>
  
  <p>Controller:</p>
  
  <pre><code>public JsonResult Action(string text, string a, int b)
      {
          return Json((List&lt;SelectListItem&gt;), JsonRequestBehavior.AllowGet);
      }
  </code></pre>
  
  <p>"text" should contain the filter text.</p>
  
  <p><a href="https://demos.telerik.com/aspnet-mvc/dropdownlist/serverfiltering" rel="noreferrer">https://demos.telerik.com/aspnet-mvc/dropdownlist/serverfiltering</a> </p>