state_machine setup

state_machine_model.rb

  state_machine :checkout_state, :initial => :address, :use_transactions => false do
    state :delivery
    state :payment
    state :confirm
    state :complete

    event :next do
      transition :from => :address, :to => :delivery
      transition :from => :delivery, :to => :payment
      transition :from => :payment, :to => :confirm
      transition :from => :confirm, :to => :complete
    end

    before_transition :to => :complete, :do => :process_payments!
    after_transition :to => :complete, :do => :finalize!
  end