Ruby on Rails Enum Decleration.rb

class User < ActiveRecord::Base
  enum :role, [:admin,:moderator,:user]

  # You can optionally add this function to your model 
  # and it will be called after each change of the role for callbacks you might need
  def role_changed(from,to) 
    puts "The role changed from #{from} to #{to}"
  end

end

Ruby on Rails Enum Usage.rb

# Access through enum name
user.role #returns the user's current role
user.role = :admin # set the user's role to admin

# Access through enum values
user.admin? # returns true if user is currently an admin
user.moderator! # set the user's role to moderator and saves the user

# General enum functions
User::ROLES # returns all available roles of the user