Question

I have an .aspx page which creates a column of check boxes within a table using the ID to name it as such

<asp:TemplateField HeaderText="Select">
  <ItemTemplate>
    <asp:CheckBox ID="testCheck"  runat="server" AutoPostBack="true" />
  </ItemTemplate>                   
</asp:TemplateField>

Later in the C# portion of the code I am attempting to retrieve the value of the check box by using the following code

CheckBox chk = (CheckBox)gridRow.FindControl("testCheck");

Ideally I would like to remove the two string and hold the value in a common constant, is there any way to do this?

Answer 1

Sorry, no, there’s no way to do exactly what you want. You’ll still wind up with two occurrences of the string:

<asp:CheckBox ID="testCheck"  runat="server" AutoPostBack="true" />

and

public const string TestCheckName = "testCheck";

later

CheckBox chk = (CheckBox)gridRow.FindControl(TestCheckName );

Note that the problem isn’t so much constants, as the ASP.NET markup syntax. You could do something like this:

<asp:CheckBox ID="<%= TestCheckName %>"  runat="server" AutoPostBack="true" />

but that seems a little silly.

---

Ok, this doesn’t work at all, and here’s why:

In the declaration of the CheckBox, testCheck isn’t just a string. If it were a string, then the <%# %> syntax for databinding would work. The property would be set to that string value during the DataBinding event.

However, the ID property isn’t just a string property – it’s what the designer and page parser will use to create a field with that name. Therefore, it must be set to a constant value.

The analogy would be having code like this:

protected CheckBox testCheck;

You can’t use a string expression to create the name of a class member.