Databound drop down list - initial value

Question

How do I set the initial value of a databound drop down list in ASP.NET?

For instance, I want the values, but the first value to display should be -- Select One ---, with a null value.

Answer 1

I think what you want to do is this:

<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true">     <asp:ListItem Text="--Select One--" Value="" />    </asp:DropDownList> 

Make sure the 'AppendDataBoundItems' is set to true or else you will clear the '--Select One--' list item when you bind your data.

If you have the 'AutoPostBack' property of the drop down list set to true you will have to also set the 'CausesValidation' property to true then use a 'RequiredFieldValidator' to make sure the '--Select One--' option doesn't cause a postback.

<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="DropDownList1"></asp:RequiredFieldValidator> 

Answer 2

I know this is old, but a combination of these ideas leads to a very elegant solution:

Keep all the default property settings for the DropDownList (AppendDataBoundItems=false, Items empty). Then handle the DataBound event like this:

protected void dropdown_DataBound(object sender, EventArgs e) {     DropDownList list = sender as DropDownList;     if (list != null)         list.Items.Insert(0, "--Select One--"); } 

The icing on the cake is that this one handler can be shared by any number of DropDownList objects, or even put into a general-purpose utility library for all your projects.