title: add search functionality on DropDownListFor
body: <p>I am wondering if any one could help me with a issue I am facing. I am trying to create a search on a DropDownListFor using razor. </p>
  
  <pre><code>private List&lt;SelectListItem&gt; LoadStockitems()
  {
      List&lt;SelectListItem&gt; selectItems = new List&lt;SelectListItem&gt;();
      foreach (var role in GetStockItemsFromDB())
      {
          SelectListItem listItem = new SelectListItem();
          listItem.Value = role.StockCode;
          listItem.Text = role.Description;
          selectItems.Add(listItem);
      }
      return selectItems;
  }
  
  ViewBag.AllStockList  = LoadStockitems();
  </code></pre>
  
  <p>View</p>
  
  <pre><code>@Html.DropDownListFor(x =&gt;
      x.StockCode,
      (IEnumerable&lt;SelectListItem&gt;)ViewBag.AllStockList,
      new {
          @class = "form-control",
          @Value = @Model.Description,
          onchange = "this.form.submit();"
  })
  </code></pre>
  
  <p>I can do this using Html but I can not figure out how to do using razor. 
  In HTML, </p>
  
  <pre><code>@using (Html.BeginForm("Hello", "Hello"))
  {
      &lt;div class="form-group"&gt;
          &lt;label class="control-label"&gt; Select A Customer &lt;/label&gt;
          &lt;select class="selectpicker bs-select form-control"
                  name="CustomerID"
                  onchange="this.form.submit()"
                  data-show-subtext="true"
                  data-live-search="true"&gt;
              @foreach (var Customer in @Model.CustomerSelect)
              {
                  &lt;option value="@Customer.CustomerID"
                          data-subtext="@Customer.ContactName"&gt;
                      @Customer.Name
                  &lt;/option&gt;
              }
          &lt;select&gt;
          &lt;input type="hidden" name="SearchButton" value="true"&gt;
      &lt;/div&gt;
  }
  </code></pre>
  
  <p>How can you create a search on a DropDownListFor and is there anything like subtext attribute...?</p>