Question

what goes in the code behind for the Server Validate event of a Custom Validator, which is attempting to validate a set of 2 radiobuttons?

Answer 1

Mainly you need to specify your custom logic and if everything passes satisfactorily you would set args.IsValid = true; otherwise, you would set it to false. The set ErrorMessage will appear if validation fails.

The basic outline is as follows:

protected void CustomServerValidate(object sender, ServerValidateEventArgs args)
{
    if (/* custom logic */)
    {
        args.IsValid = false; // failed validation
    }
    else
    {
        args.IsValid = true; // passed validation
    }
}

For example, given radio buttons r1 and r2 you might have logic like this to ensure one of them is selected:

protected void CustomServerValidate(object sender, ServerValidateEventArgs args)
{
    if (!r1.Checked && !r2.Checked)
    {
        args.IsValid = false;
    }
    else
    {
        args.IsValid = true;
    }
}

The above could’ve been assigned directly in one line, but is expanded for clarity. As another example, you may have an “Other” type of button with an associated “If you selected other, please explain:” textbox. You could check if the other radio is selected, then check the textbox etc.