如何在将父实体保存到数据库的同时保存子实体？

Question

我正在尝试开发一个小型电子商务项目。我有一个篮子和篮子项目实体。我只是想当我为客户保存购物篮时，我想把购物篮项目保存在数据库中。我认为我不应该为篮子项目创建存储库。我应该能够保存篮子项目，同时使用篮子存储库保存篮子。

public class Basket extends BaseModel {

    @Column(nullable = false)
    private BigDecimal price;

    private BigDecimal discountPrice = BigDecimal.ZERO;
    private BigDecimal taxPrice = BigDecimal.ZERO;
    private BigDecimal shippingPrice = BigDecimal.ZERO;

    @Column(nullable = false)
    private BigDecimal totalPrice;

    @OneToMany(mappedBy = "basket", cascade = CascadeType.PERSIST)
    private Set<BasketItem> items = new HashSet<>();

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "customer_id", nullable = false)
    private Customer customer;

}

public class BasketItem extends BaseModel {

    @ManyToOne(optional = false)
    private Basket basket;

    @ManyToOne(optional = false)
    private Product product;

    @Column(nullable = false)
    private Long quantity;
    @Column(nullable = false)
    private BigDecimal price = BigDecimal.ZERO;
    private BigDecimal discountPrice = BigDecimal.ZERO;
    private BigDecimal taxPrice = BigDecimal.ZERO;
    private BigDecimal shippingPrice = BigDecimal.ZERO;
}

在这里，我试图通过篮子服务获得一个篮子项目，并将其设置为篮子实体并保存它。

public class BasketServiceImpl implements BasketService{

    private final CustomerRepository customerRepository;
    private final BasketRepository basketRepository;
    private final BasketItemConverter basketItemConverter;

    @Override
    public void addBasketItemToBasket(Long customerId, AddBasketItemDTO addBasketItemDTO) {
        //Find customer
        Customer customer = customerRepository.findById(customerId).orElseThrow(
                () -> new BusinessServiceOperationException.CustomerNotFoundException("Customer not found")
        );
        //Convert AddBasketItemDto to BasketItem
        BasketItem basketItem = basketItemConverter.toBasketItem(addBasketItemDTO);
        Set<BasketItem> basketItemsList = new HashSet<BasketItem>();
        Basket basket = new Basket();
        basketItemsList.add(basketItem);

        basket.setItems(basketItemsList);
        basket.setCustomer(customer);
        basket.setPrice(BigDecimal.ZERO);
        basket.setTotalPrice(BigDecimal.ZERO);
        basketRepository.save(basket);
    }
}

我有什么问题？我有个例外。

{
    "errorMessage": "detached entity passed to persist: org.patikadev.orderexample.model.BasketItem; nested exception is org.hibernate.PersistentObjectException: detached entity passed to persist: org.patikadev.orderexample.model.BasketItem"
}

Answer 1

是的，如果篮子有适当的持久链接，你不需要篮子项目存储库。但是你必须先保存项目，然后将其添加到篮子中，并在最后保存篮子。