Validating DropDownList using RequiredFieldValidator

In ASP.NET we need to validate DropDownList controls. But validating the DropDownList control with RequiredFieldValidator is not a straight forward as validating a TextBox control with RequiredFieldValidator. It requires little extra work.

Following are the steps for validating a DropDownList with RequiredFieldValidator
Step 1: Create a DropDownList control

   1:  <asp:DropDownList ID="ddlFruit" runat="server" Height="22px" Width="200px">

   2:      <asp:ListItem>- Select -</asp:ListItem>

   3:      <asp:ListItem>Apple</asp:ListItem>

   4:      <asp:ListItem>Orange</asp:ListItem>

   5:      <asp:ListItem>Banana</asp:ListItem>

   6:      <asp:ListItem>Pineapple</asp:ListItem>

   7:  </asp:DropDownList>

Step 2: Add a RequiredFieldValidator

   1:  <asp:RequiredFieldValidator ID="rfvFruit" runat="server" ErrorMessage="Select a Fruit"

   2:  ControlToValidate="ddlFruit" ValidationGroup="Add">

   3:  </asp:RequiredFieldValidator>

Step 3: Add an Initial Value Property to RequiredFieldValidator

   1:  InitialValue="- Select -"

Complete Code

   1:  <table style="width: 100%;">

   2:      <tr>

   3:          <td align="right">

   4:              Fruit:

   5:          </td>

   6:          <td style="vertical-align: middle;">

   7:              <asp:DropDownList ID="ddlFruit" runat="server" Height="22px" Width="200px">

   8:                  <asp:ListItem>- Select -</asp:ListItem>

   9:                  <asp:ListItem>Apple</asp:ListItem>

  10:                  <asp:ListItem>Orange</asp:ListItem>

  11:                  <asp:ListItem>Banana</asp:ListItem>

  12:                  <asp:ListItem>Pineapple</asp:ListItem>

  13:              </asp:DropDownList>

  14:              <asp:RequiredFieldValidator ID="rfvFruit" runat="server" ErrorMessage="Select a Fruit"

  15:                  ControlToValidate="ddlFruit" InitialValue="- Select -" ValidationGroup="Add">

  16:              </asp:RequiredFieldValidator>

  17:          </td>

  18:      </tr>

  19:      <tr>

  20:          <td>

  21:          </td>

  22:          <td>

  23:              <asp:Button ID="btnAdd" runat="server" Text="Save" ValidationGroup="Add" Width="70px" />

  24:          </td>

  25:      </tr>

  26:  </table>