class NotFound < StandardError; end class ApplicationController < ActionController::Base protect_from_forgery rescue_from(ActiveRecord::RecordNotFound) { render 'exceptions/not_found' } class Unauthorized < Exception; end helper_method :current_user def current_user @current_user ||= User.find_by_id(session[:user_id]) if session[:user_id] end def current_user=(user) if user @current_user = user session[:user_id] = user.id else @current_user = nil session[:user_id] = nil end end private def ensure_authenticated! raise Unauthorized unless current_user end end