From: "Jose tomas R." Date: 2011-01-04T03:14:43+09:00 Subject: Validates is exists Event has_and_belongs_to_many :users User has_and_belongs_to_many :events Im trying to verify that user doesnt signup more than one time def signup @event = Event.find(params[:id]) @user = current_user respond_to do |format| if @event.users.find(@user) != @user.id @user.events << @event format.html { redirect_to(@event, :notice => 'You where successfully Signed Up.') } format.xml { head :ok } else format.html { redirect_to(@event, :notice => 'You where already Signed Up.') } format.xml { head :ok } end end end but i think that's no ok, i get this message, when the user havent signed up: Couldn't find User with ID=2 [WHERE ("events_users".event_id = 7 )] -- Posted via http://www.ruby-forum.com/.