Cart

    # File app/models/cart.rb, line 4
 4:   def add_product(product_id)

 5:     current_item = line_items.find_by_product_id(product_id)

 6:     if current_item

 7:       current_item.quantity += 1

 8:     else

 9:      current_item = line_items.build(:product_id => product_id)

10:     end

11:     current_item

12:   end

    # File app/models/cart.rb, line 18
18:   def total_items

19:     line_items.sum(:quantity)

20:   end

    # File app/models/cart.rb, line 14
14:   def total_price

15:     line_items.to_a.sum { |item| item.total_price }

16:   end