Cfrtjryk

I have an object (ShoppingCart) that has a list of CartItems, which contains the related Product and the quantity bought.

public class ShoppingCart extends BaseEntity {



    @OneToMany(mappedBy = "shoppingCart", cascade = CascadeType.ALL, orphanRemoval = true)

    private List<CartItem> cartItems = new ArrayList<>();



    @DateTimeFormat(pattern = "dd/MM/yyyy hh:MM:ss")

    private LocalDateTime dateTime;



    @Enumerated

    private PaymentMethod paymentMethod = PaymentMethod.CASH;

public class CartItem extends BaseEntity {



    @ManyToOne

    private Product product;



    @ManyToOne(fetch = FetchType.LAZY)

    @JoinColumn

    private ShoppingCart shoppingCart;

public class Product extends BaseEntity {



    @NotEmpty

    private String name;



    private double price;



    private int quantity;

I have a view that sums all shopping carts, and I don't know if I should store that sum inside ShoppingCart entity, or iterate to find the sum.
Here's the code, right now I'm iterating.

@GetMapping("/")

    public String getProduct(@ModelAttribute("reportDto") ReportDto reportDto, Model model) {



        double total = 0, cash = 0, credit = 0, debit = 0;

        int quantity;

        List<ShoppingCart> results;

        if (reportDto.getBeginDate() == null || reportDto.getEndDate() == null) {

            results = shoppingCartService.findAll();

        } else {

            results = shoppingCartService.findByDateTimeBetween(reportDto.getBeginDate(), reportDto.getEndDate());

        }

        total = results.stream()

                .mapToDouble(shoppingCart -> shoppingCart.getCartItems().stream()

                        .mapToDouble(cartItem -> cartItem.getProduct().getPrice() * cartItem.getQuantity()).sum())

                .sum();

        quantity = results.stream().mapToInt(

                shoppingCart -> shoppingCart.getCartItems().stream().mapToInt(cartItem -> cartItem.getQuantity()).sum())

                .sum();



        cash = results.stream().filter(shoppingCart -> shoppingCart.getPaymentMethod().isCash())

                .mapToDouble(shoppingCart -> shoppingCart.getCartItems().stream()

                        .mapToDouble(cartItem -> cartItem.getProduct().getPrice() * cartItem.getQuantity()).sum())

                .sum();



        credit = results.stream().filter(shoppingCart -> shoppingCart.getPaymentMethod().isCredit())

                .mapToDouble(shoppingCart -> shoppingCart.getCartItems().stream()

                        .mapToDouble(cartItem -> cartItem.getProduct().getPrice() * cartItem.getQuantity()).sum())

                .sum();



        debit = results.stream().filter(shoppingCart -> shoppingCart.getPaymentMethod().isDebit())

                .mapToDouble(shoppingCart -> shoppingCart.getCartItems().stream()

                        .mapToDouble(cartItem -> cartItem.getProduct().getPrice() * cartItem.getQuantity()).sum())

                .sum();

        model.addAttribute("quantity", quantity);

        model.addAttribute("cash", cash);

        model.addAttribute("credit", credit);

        model.addAttribute("debit", debit);

        model.addAttribute("total", total);

        return "reports/reports";

    }

Also, any feedback regarding the code will be appreciated!