Default Ability Class with Devise, Rolify and Cancan

ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new # guest user (not logged in)

    if user.has_role? :admin
        can :manage, :all
    elsif user.has_role? :user
        can :read, :all
        can :manage, :all, owner: user
    else
        can :read, :all
    end
  end
end