Tuesday, May 04, 2010

Multiple controls, same ID, different containers!

I was minding my own business doing this ridiculous ASP.Net project and suddenly I am hit with: "Multiple controls with the same ID 'lbTitle' were found. FindControl requires that controls have unique IDs.". I was using this web control that contained two others, each of them having a lbTitle control.

If you think about it, it does make sense to throw this exception when the FindControl method is used in the parent control. Which control did I mean? But the error appears even if the FindControl is used inside one of the child controls, what is up with that?

As a secondary thought, I wasn't using any FindControl. It seems that what does is the AssociatedControlID property of the Label control. Therefore I will set the HtmlTextWriterAttribute.For attribute manually to resolve this. Pretty damn ugly, if you ask me!

Update: My fault! The controls needed to implement the INamingContainer interface. It's not that the ClientID was not different, but FindControl works by going to the NamingContainer control and finding then children by ID. Too bad that you can't just specify the ClientID and be done with it, but that's that.