As described, Rails is looking for the view to have a method called
'admin?' somewhere (possibly in a helper method) but it does not. If
you have an object that you want to share between the controller and
the view that has the 'admin?' method on it then you normally do that
by defining an instance variable on the controller which is then
copied over to the view for you by Rails.
It appears that you're using acts_as_authenticated or
restful_authentication. If that's the case then you probably want to
use a method on @current_user.
Hey instead of calling as if admin? do it like this...
if @controller.admin@controller is the instance variable of current controller which is
forum in your case