Question

我正在Web应用程序中设置客户端购物车。在添加Shopping Cart类和他的服务之前，一切都还好。现在，当我尝试启动Spring应用程序时，将显示此错误：

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

我搜索了一个解决方案，但发现应用程序的实体存在问题。一种解决方案是将（cascade = CascadeType.ALL）添加到导致错误的实体。但是我的课程已经有了，在购物车课程开始之前一切都很好。

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：

在此类方法中，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;
    }

此错误将终止Spring应用程序，并且仅在MySql中创建表而不添加行。

修改1： 当我尝试将新用户添加到我的应用程序时，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（运行），则服务器运行得很好，直到应创建新用户为止，然后出现错误。

Answer 1

您要从roles中持久保存userRole，然后将其分配给用户，但是在保存后，您不会将持久实体分配给角色，因此roles userRole中的不再与持久化的相同，并且也没有生成的id。当您保存一个实体，然后将其或父级作为值添加到另一个实体并且没有完全级联时，您将添加另一个对象。这意味着，使用保存时返回的对象并将其重新分配给您保存的对象，然后应该没问题，或者在所有地方使用级联，仅保存1个对象。

TLDR； userRoles'role与数据库中的Role实体不同。

编辑1：

将Set<UserRole> userRoles更改为List<UserRole> userRoles（否则必须转换100次，因为遍历aSet时无法替换Set的值）然后替换

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

使用

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

如何修复'org.hibernate.TransientPropertyValueException'？

1 个答案: