我的 Spring Boot 应用程序遇到问题，无法将项目列表保存到购物车对象

Question

我正在尝试制作我的第一个 Spring Boot 应用程序，并且我想将项目列表添加到购物车。但由于某种原因，项目列表没有保存到数据库中。

我添加了端点产生的结果的屏幕截图。

到目前为止我的代码：

账户类别：

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Entity
public class Account {
    @GeneratedValue
    @Id
    private Long id;
    @Column(nullable = false)
    private String name;
    @Column(unique = true, nullable = false)
    private String email;
    @Column(length = 1000, nullable = false)
    private String password;

    private LocalDateTime createdOn;
    {
        createdOn = LocalDateTime.now();
    }
    private LocalDateTime lastUpdateOn;

    @JsonManagedReference
    @OneToOne(cascade = CascadeType.PERSIST)
    private Cart cart;

    // Constructor for Seeder
    public Account(String name, String email, String password) {
        this.cart = new Cart();
        this.name = name;
        this.email = email;
        this.password = password;
        this.createdOn = LocalDateTime.now();
    }
}

推车类：

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Cart {
    @GeneratedValue
    @Id
    private Long id;

    @JsonBackReference
    @OneToOne
    private Account account;

    private LocalDateTime createdOn;
    {
        createdOn = LocalDateTime.now();
    }
    private LocalDateTime lastUpdateOn;

    @JsonManagedReference
    @OneToMany(mappedBy = "cart")
    private List<Item> items;

    private String test;
}

物品类别：

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Entity
public class Item {
    @GeneratedValue
    @Id
    private Long id;

    private LocalDateTime createdOn;
    {
        createdOn = LocalDateTime.now();
    }
    private LocalDateTime lastUpdateOn;

    @JsonBackReference
    @ManyToOne
    @JoinColumn(name = "cart_id")
    private Cart cart;

    @ManyToOne
    @JoinColumn(name = "game_id")
    private Game game;
    private Integer quantity;

    public Item(Game game, Integer quantity) {
        this.game = game;
        this.quantity = quantity;
    }
}

推车控制器：

@RequestMapping("/carts")
@RestController
public class CartController {
    @Autowired
    CartService cartService;

    @GetMapping
    public List<Cart> getAllCarts() {
        return cartService.getCarts();
    }

    @GetMapping("/{id}")
    public Cart getCartById(@PathVariable Long id) {
        return cartService.getCartById(id);
    }

    @PutMapping("/add/{id}")
    public ResponseEntity<Cart> addItemsToCart(@PathVariable Long id, @RequestBody List<Item> items) {
            if (cartService.updateCartContents(id, items)) {
                return ResponseEntity.status(HttpStatus.OK).build();
            } else {
                return ResponseEntity.status(HttpStatus.CONFLICT).build();
            }
    }

    @DeleteMapping("/{id}")
    public ResponseEntity<Cart> deleteCart(@PathVariable Long id) {
        if (cartService.deleteCart(id)) {
            return ResponseEntity.status(HttpStatus.OK).build();
        } else {
            return ResponseEntity.status(HttpStatus.CONFLICT).build();
        }
    }

    @PutMapping("clearcart/{id}")
    public ResponseEntity<Cart> clearCart(@PathVariable Long id){
        if (cartService.clearCart(id)){
            return ResponseEntity.status(HttpStatus.OK).build();
        } else {
            return ResponseEntity.status(HttpStatus.CONFLICT).build();
        }
    }

    @PutMapping("removeitem/{id}")
    public ResponseEntity<Cart> removeCartItems(@PathVariable Long id, @RequestBody Item item){
        if (cartService.removeCartItem(id,item)){
            return ResponseEntity.status(HttpStatus.OK).build();
        } else {
            return ResponseEntity.status(HttpStatus.CONFLICT).build();
        }
    }

    // check out. dus zet cart om in purchase en clear de cart
    @PutMapping("checkout/{id}")
    public ResponseEntity<Cart> checkout(@PathVariable Long id){
        try{
            cartService.checkout(id);
            return ResponseEntity.status(HttpStatus.OK).build();
        } catch (IllegalArgumentException e) {
            return ResponseEntity.status(HttpStatus.CONFLICT).build();
        }
    }
}

和购物车服务：

@Service
public class CartService {
    @Autowired
    CartRepository cartRepository;
    @Autowired
    ItemRepository itemRepository;
    @Autowired
    PurchaseRepository purchaseRepository;

    public List<Cart> getCarts(){
        return cartRepository.findAll();
    }

    public Cart getCartById(Long id){
        return cartRepository.findById(id).orElseThrow();
    }

    public boolean updateCartContents(Long id, List<Item> items){
        Optional<Cart> optionalCart = cartRepository.findById(id);
        if (optionalCart.isPresent()) {
            Cart cart = optionalCart.get();
            cart.getItems().addAll(items);
            System.out.println("cart items before saving: " + cart.getItems());
            cartRepository.save(cart);
            System.out.println("cart items after saving: " + cart.getItems());
            return true;
        } else {
            return false;
        }
    }

    public boolean deleteCart(Long id){
        if(cartRepository.findById(id).isPresent()){
            cartRepository.deleteById(id);
            return true;
        }else{
            return false;
        }
    }

    public boolean clearCart(Long id){
        if(cartRepository.findById(id).isPresent()){
            Cart cart = cartRepository.findById(id).orElseThrow();
            cart.getItems().clear();
            cartRepository.save(cart);
            return true;
        }else{
            return false;
        }
    }

    public boolean removeCartItem(Long id, Item itemToRemove){
        if(cartRepository.findById(id).isPresent()){
            Cart cart = cartRepository.findById(id).orElseThrow();
            cart.getItems().remove(itemRepository.findById(itemToRemove.getId()).orElseThrow());
            cartRepository.save(cart);
            return true;
        }else{
            return false;
        }
    }

    public void checkout(Long id) throws IllegalArgumentException{
        Cart cart = cartRepository.findById(id).orElseThrow(IllegalArgumentException::new);
        //Purchase purchase = new Purchase();
        //purchase.setPurchasedItems(cart.getItems());
        //purchaseRepository.save(purchase);
        clearCart(id);
    }
}

我添加了一个名为 test 的字符串变量，以查看购物车是否根本没有更新，但是当我调整它时，它确实显示在购物车中。所以问题似乎特别出在项目列表上。我添加了一个控制台日志来调用该列表，并且在我的控制台中它确实记录了它，就像添加了项目一样。

控制台日志输出如下： `保存前的购物车项目：[Item{id=1,createdOn=2024-05-05T12:49:57.343516400,lastUpdateOn=null,cart=null,game=null,quantity=null},Item{id=2,createdOn= 2024-05-05T12：49：57.344485400，lastUpdateOn = null，购物车= null，游戏= null，数量= null}，项目{id = 3，createdOn = 2024-05-05T12：49：57.344485400，lastUpdateOn = null，购物车=空，游戏=空，数量=空}]

保存后的购物车项目：[Item{id=1,createdOn=2024-05-05T12:49:53.806481,lastUpdateOn=null,cart=null,game=com.united.Gamestore.Game.Game@2f5cee8,quantity=1 }，项目{id = 2，createdOn = 2024-05-05T12：49：53.809481，lastUpdateOn = null，cart = null，game = com.united.Gamestore.Game.Game@7cedf75c，数量= 1}，项目{id =3、createdOn=2024-05-05T12:49:53.811481、lastUpdateOn=null、cart=null、game=com.united.Gamestore.Game.Game@6f5d6a00、数量=1}]`

Answer 1

您的多对一/一对多关系是双向的。当您向列表添加新条目时，您还必须在目标实体中设置引用。在购物车实体中实现一个辅助方法，如下所示：

public void addItem(Item item) {
    items().add(item);
    item.setCart(this);
}

与此类似，您应该实现一个删除条目的方法：

public void removeItem(Item item) {
    items().remove(item);
    item.setCart(null);
}

这样您就可以在一处实现，并且关系将正确同步。

基于：https://vladmihalcea.com/the-best-way-to-map-a-onetomany-association-with-jpa-and-hibernate/