##shop_controller.rb
def checkout
    if @cart.items.empty?
      redirect_to_show("Your cart is empty")
    else
      @deal = Deal.new_shopping_deal
      current_org.deals << @deal
      @deal.add_orders_from_cart(@cart)
      if @deal.save
        session[:cart] = nil
        redirect_to_show("Thank you for your order")
      else
        render :action => :show
      end
    end
end

##deal.rb
class Deal < ActiveRecord::Base
 has_many :orders, :dependent => :destroy

 # gets called in a controller
 def add_orders_from_cart(cart)
    cart.items.each do |item|
      ord = Order.from_cart_item(item)
      orders << ord
      @@yummy = true
    end
  end
end


##order.rb
class Order < ActiveRecord::Base
  after_save :save_duties
  has_many :duties, :dependent => :destroy
  validates_associated :duties

  private

  def save_duties
    regulations = Regulation.find_all_by_product_id(self.product_id)
    #order_val = self.ord_value

    if self.new_record?       # for new order -> never goes here!
#      for reg in regulations
#        arr =  calc_duty_values(reg, ord_value)
#        tduty = create_duty(reg, arr)
#        duties.create(tduty)
#      end
    else                            # for existing order
      duties.clear
      for regu in regulations
        arr =  calc_duty_values(regu, ord_value)
        tduty = create_duty(regu, arr)
        duties.create(tduty)
      end
    end
  end # end-save duties
end