# File app/models/cart.rb, line 7 def add_product(product_id) current_item = line_items.find_by(product_id: product_id) if current_item current_item.quantity += 1 else current_item = line_items.build(product_id: product_id) current_item.price = current_item.product.price end current_item end
START:#total_price
# File app/models/cart.rb, line 20 def total_price line_items.to_a.sum { |item| item.total_price } end