java - 如何修复 ' org.hibernate.TransientPropertyValueException'？

Question

我正在我的网络应用程序中设置客户端购物车。在添加购物车类和他的服务之前一切都很好。现在，当我尝试启动 Spring 应用程序时，会显示此错误:

Caused by: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : com.myBookstoreProject.domain.security.UserRole.role -> com.myBookstoreProject.domain.security.Role

我寻找解决方案，但发现我的应用程序实体存在问题。解决方案是将 (cascade=CascadeType.ALL) 添加到导致错误的实体。但我的类(class)已经有了它，并且在购物车类(class)之前一切都很好。

• 用户类别:

  @Entity
  public class User implements UserDetails {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      @Column(name = "id", nullable = false, updatable = false)
      private Long id;
      private String username;
      private String password;
      private String firstName;
      private String lastName;
  
      @Column(name = "email", nullable = false, updatable = false)
      private String email;
      private String phone;
      private boolean enabled = true;
  
      @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
      @JsonIgnore 
      private Set<UserRole> userRoles = new HashSet<>();
  
      @OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
      private List<UserShipping> userShippingList;
  
      @OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
      private List<UserPayment> userPaymentList;
  
      @OneToOne(cascade = CascadeType.ALL, mappedBy = "user")
      private ShoppingCart shoppingCart;
  
      // getters and setters..
  }
  

• 角色

  @Entity 
  public class Role {
  
      @Id
      private int roleId;
      private String name;
  
      @OneToMany(mappedBy = "role", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
      private Set<UserRole> userRoles = new HashSet<UserRole>();
  
      // getters and setters..
  }
  

• UserRole 类:

  @Entity
  @Table(name = "user_role")
  public class UserRole {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Long userRoleId;
  
      @ManyToOne(fetch = FetchType.EAGER)
      @JoinColumn(name = "user_id")
      private User user;
  
      @ManyToOne(fetch = FetchType.EAGER)
      @JoinColumn(name = "role_id")
      private Role role;
  
      // getters and setters..
  }
  

• 购物车:

  @Entity
  public class ShoppingCart {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Long id;
      private BigDecimal GrandTotal;
  
      @OneToMany(mappedBy="shoppingCart", cascade=CascadeType.ALL, fetch=FetchType.LAZY)
      @JsonIgnore
      private List<CartItem> cartItemList;
  
      @OneToOne(cascade=CascadeType.ALL)
      private User user;
      // getters and setters...
  }
  

• 购物车服务实现:

  @Service
  public class ShoppingCartServiceImpl implements ShoppingCartService {
  
      @Autowired
      private CartItemService cartItemService;
  
      @Autowired
      private ShoppingCartRepository shoppingCartRepository;
  
      @Override
      public ShoppingCart updateShoppingCart(ShoppingCart shoppingCart) {
          BigDecimal cartTotal = new BigDecimal(0);
  
          List<CartItem> cartItemList = cartItemService.findByShoppingCart(shoppingCart);
  
          for (CartItem cartItem : cartItemList) {
              if (cartItem.getBook().getInStockNumber() > 0) {
                  cartItemService.updateCartItem(cartItem);
                  cartTotal = cartTotal.add(cartItem.getSubtotal());
              }
          }
  
          shoppingCart.setGrandTotal(cartTotal);
  
          shoppingCartRepository.save(shoppingCart);
  
          return shoppingCart;
      }
  
  }
  

• 用户服务实现:

在这个类方法中，我添加了“@Transactional”和 5 行购物车，然后出现错误

@Override
@Transactional
    public User createUser(User user, Set<UserRole> userRoles) throws Exception {
        User localUser = userRepository.findByUsername(user.getUsername());

        if (localUser != null) {
            LOG.info("user {} already exists. Nothing will be done.", user.getUsername());
        } else {
            for (UserRole ur : userRoles) {
                roleRepository.save(ur.getRole());
            }

            user.getUserRoles().addAll(userRoles);

            ShoppingCart shoppingCart = new ShoppingCart(); // 1
            shoppingCart.setUser(user); // 2
            user.setShoppingCart(shoppingCart); // 3

            user.setUserShippingList(new ArrayList<UserShipping>()); //4
            user.setUserPaymentList(new ArrayList<UserPayment>()); // 5

            localUser = userRepository.save(user);
        }
        return localUser;
    }

此错误会终止 Spring 应用程序，并且仅在 MySql 中创建表而不添加行。

编辑 1: 当我尝试向我的应用程序添加新用户时会出现问题。这是我的引导主类:

@SpringBootApplication
public class BookstoreProjectApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(BookstoreProjectApplication.class, args);
    }

    @Autowired
    private UserService userService;

    @Override
    public void run(String... args) throws Exception {
        User user1 = new User();
        user1.setFirstName("New");
        user1.setLastName("User");
        user1.setUsername("j");
        user1.setPassword(SecurityUtility.passwordEncoder().encode("p"));
        user1.setEmail("newUser@gmail.com");
        Set<UserRole> userRoles = new HashSet<>();
        Role role1 = new Role();
        role1.setRoleId(1);
        role1.setName("ROLE_USER");
        userRoles.add(new UserRole(user1, role1));

        userService.createUser(user1, userRoles);
    }
}

如果我注释方法主体(run)，服务器运行得很好，直到创建新用户，然后出现错误。

Answer 1

您正在坚持 roles来自您的userRole然后将它们分配给用户，但在保存它们后，您不会将持久实体分配给角色，因此 roles在userRole与持久化的不再相同，也没有生成的 id 。当您保存一个实体，然后将其或父实体作为值添加到另一个实体并且没有完全级联时，您将添加一个不同的对象。这意味着，使用 save 的返回对象并将其重新分配给您保存的对象，然后应该没问题，或者在各处使用级联并仅保存 1 个对象。

TLDR； userRoles 'role与 Role 不一样数据库中的实体。

编辑1:

更改Set<UserRole> userRoles至List<UserRole> userRoles (否则你必须将其转换大约 100 次，因为你无法在遍历 Set 时替换它的值)然后替换

for (UserRole ur : userRoles) {
  roleRepository.save(ur.getRole());
}

与

for (int i = 0; i < userRoles.size(); i++) {
  userRoles.get(i).setRole(roleRepository.save(userRoles.get(i).getRole())
}