Casting Eval("bitValue") as Bool

Question

I have a list view with a HyperLink control within the ItemTemplate. I want to display the link if a returned value is 0 (false), and not display the link if it is 1 (true).

So far I have this:

<asp:HyperLink runat="server" ID="lnkReview"
  NavigateUrl='<%# Eval("EnquiryID", @"selectcompany.aspx?enq={0}")%>'
  Text="Review Enquiry"
  Visible='<%# ((bool)Eval("Locked"))==true? false : true %>' />

...but this renders an 'Specified cast is not valid' exception.

Examples I've seen elsewhere suugest this should work. I can confirm that the Locked column only returns 0 or 1 (from SQL Server) - surely these should be easily cast from bit/int to bool??

Answer 1

Give this a try:

bool.Parse(Eval("Locked").ToString())

Answer 2

If Locked is an int you should do this:

<%# ((int)Eval("Locked")) == 1 ? true : false %>

But then this should work too, so it returns true when Locked > 0

<%# !((int)Eval("Locked") == 0) %>

No matter it is mentioned that Locked contains 0 or 1. It is still an INT which can for some reason contain values > 1. Therefore i find it good practice to do the check on == 0 instead of == 1. We don't know what Locked is used for and in the future the design could change so that Locked can contain a value > 1.

Answer 3

SQL is a strange world where bits can have three states 0, 1 and null! So this means that Eval("Locked") is a nullable type bool, not a plain bool A cast to bool will not be valid if the bit value is null, you have to check that first:

(Eval("Locked")!=null && (bool)Eval("Locked")==true)

This assumes that null should be mapped to false.