ingramchen

class OrderService {

   CartDto addItem(cartId, productId) {
      var cart = cartRichDao.findById(cardId)
      var prod = productRichDao.findById(productId)
      
      // service layer not allow mutate Cart entity directly, delegate to rich DAO
      var updatedCart = cartRichDao.addItem(cart, prod, clock.instant())
      return updatedCart.toDto()