how to give back the hand to AR error handling ?

rubyonrails-talk
1

In controller I use to raise some specific error as follows :

include CustomErrors

rescue_from NoGuestFound,NoHostFound,NoInvitation,WrongPass do |e|   flash[:message] = e.message   redirect_to :action => :index end

def lambda   ...   @guest.is_invited_by?(@host) or raise CustomError1.new 'context message'   ... end

I find this way of doing pretty OK, but for AR model validation I'd like to give back the end to the Active Record standard validation process. I can't find good doc on how to do so and how AR validation works exactly...

if anybody has a better way to deal with error handling or if you could give me some smart links, would appreciate !