title: Handle user control dropdownlist selected index change event in aspx page
body: <p>I have create the user control and add the same in aspx code behind. I want to handle the selected index change event for dropdownlist in aspx page. Kindly help me to do this.</p>
  
  <pre><code>&lt;div class="row"&gt;
      &lt;div class="col-lg-2"&gt;
          &lt;asp:Label ID="lbl_parent" runat="server" Text="Parent Node" CssClass="control-label"&gt;&lt;/asp:Label&gt;
      &lt;/div&gt;
      &lt;div class="col-lg-6"&gt;
          &lt;asp:DropDownList ID="ddl_parent" runat="server" CssClass="form-control" AutoPostBack="true"&gt;
          &lt;/asp:DropDownList&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  phContactDetails.Controls.Add(LoadControl("~/UserControl/WUC_DisLabelControl.ascx"));
  
  foreach (var control in phContactDetails.Controls)
              {
                  var usercontrol = control as WUC_DisLabelControl;
                  DropDownList ddl_parenrt = ((DropDownList)usercontrol.FindControl("ddl_parent"));
                  ddl_parenrt.SelectedIndexChanged += new EventHandler(ddlparent_SelectedIndexChanged);
  }
  
  protected void ddlparent_SelectedIndexChanged(object sender, EventArgs e)
          {
              throw new NotImplementedException(); //Not Firing 
          }
  </code></pre>