Using duplicate asp.net control IDs in different conditional blocks / validators

Question

Hi,

I have an asp page that renders controls based on a Request parameter. Simplified example:

<% if (Request.QueryString["personType"] == "D") { %>
    <asp:TextBox ID="TextBoxName" runat="server" Text='<%# Bind("first_name") %>' />
    <asp:TextBox ID="TextBoxSurname" runat="server" Text='<%# Bind("surname") %>' />
<% } else { %>
    <asp:TextBox ID="TextBoxName" runat="server" Text='<%# Bind("first_name") %>' />
<% } %>
<asp:RequiredFieldValidator ID="RequiredFieldValidator" runat="server"
ControlToValidate="TextBoxName" ErrorMessage="Please enter an name." />

However, the compiler and runtime are complaining that the TextBoxName is not a unque ID. But surely it is, if the output is conditional and exclusive?

I could rename them TextBoxNameA (if block) and TextBoxNameB (else block), but the odd thing is that the validator still seems to fire on TextBoxNameB, even if the validator is inside the else block and the code runs through the first block at runtime

How can I set the page to render one or the other boxes, without conflicting IDs and conflicting Validators?

Thanks for any help

Ryan

Answer 1

But server side, how is the parser supposed to distinguish the two?

And while parsing it will not be able to determine that one should be displayed and one shouldn't.

You need to give each server side control a different ID, regardless of it being displayed to the client.

You can restructure you code like this, as TextBoxName will always display (and with the same text):

<asp:TextBox ID="TextBoxName" runat="server" Text='<%# Bind("first_name") %>' />
<% if (Request.QueryString["personType"] == "D") { %>
    <asp:TextBox ID="TextBoxSurname" runat="server" Text='<%# Bind("surname") %>' />
<% } %>

And no more problem.

Answer 2

Since the Name textbox will show up regardless of the condition, you can just take that out of your if block all together and then just conditionally show the SurName textbox and that should solve your problem.

Answer 3

How about moving around your logic?

    <asp:TextBox ID="TextBoxName" runat="server" Text='<%# Bind("first_name") %>' />
<% if (Request.QueryString["personType"] == "D") { %>
<asp:TextBox ID="TextBoxSurname" runat="server" Text='<%# Bind("surname") %>' />
<% } %>
<asp:RequiredFieldValidator ID="RequiredFieldValidator" runat="server"
ControlToValidate="TextBoxName" ErrorMessage="Please enter an name." />