title: Get selectedValue dropdownList in controller at runtime
body: <p>I want to set the values of a dropdownList according to the selectedValue of another dropdownList.</p>
  
  <p>So for example :</p>
  
  <pre><code>ViewBag.Brand = new SelectList(db.Brand, "Libel", "Libel");
  ViewBag.IdModel = new SelectList(db.Model.Where(model =&gt; model.Brand == ViewBag.Brand.SelectedValue), "IdModel", "Descriptive");
  </code></pre>
  
  <p>I know this isn't working but it's to show the logic I would like to have.</p>
  
  <p>And this is my view :</p>
  
  <pre><code>&lt;div class="form-group"&gt;
      @Html.LabelFor(model =&gt; model.IdModel, htmlAttributes: new { @class = "control-label col-md-2" })
      &lt;div class="col-md-10"&gt;
          @Html.DropDownList("IdModel", null, htmlAttributes: new { @class = "form-control" })
          @Html.ValidationMessageFor(model =&gt; model.IdModel, "", new { @class = "text-danger" })
      &lt;/div&gt;
  &lt;/div&gt;
  
  &lt;div class="form-group"&gt;
      @Html.LabelFor(model =&gt; model.Brand, htmlAttributes: new { @class = "control-label col-md-2" })
      &lt;div class="col-md-10"&gt;
          @Html.DropDownList("Brand", null, htmlAttributes: new { @class = "form-control" })
          @Html.ValidationMessageFor(model =&gt; model.IdModel, "", new { @class = "text-danger" })
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Is their any simple way to do this?</p>
  
  <p>Thank's !</p>