From Rails tutorial Chapter 8 step. The existing sessions_helper does not work.

sessions_helper.rb

module SessionsHelper

  def sign_in(user)
    cookies.permanent[:remember_token] = user.remember_token
    self.current_user = user
  end

  def current_user=(user)
    @current_user = user
  end

  # taken from http://stackoverflow.com/questions/13928229/unable-to-fully-log-out-railstutorial-org-chapter-8
  def current_user
   @current_user ||= cookies[:remember_token] && User.find_by_remember_token(cookies[:remember_token])
  end

  def sign_in(user)
    cookies.permanent[:remember_token] = user.remember_token
    self.current_user = user
  end

  def signed_in?
    !current_user.nil?
  end

  def sign_out
    self.current_user = nil
    cookies.delete(:remember_token)
  end
  
end