java - POST请求的AfterMapping问题 - SPRING

Question

我有一个名为 User 的实体，它与其他实体有多种关系。好吧，我为这个实体创建了一个 DTO，并使用 MapStruct 创建了一个 Mapper。获取请求工作正常，但在尝试发布帖子时返回 500。

用户实体：

@Entity(name="user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String username;
    private String password;
    private String email;
    private Boolean admin;

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<Account> accounts;

    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private Budget budget;

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<Transaction> transactions;

用户 DTO：

public class UserDto {
    private Long id;
    private String username;
    private String password;
    private String email;
    private Boolean admin;
    private List<AccountDto> accounts;
    private BudgetDto budgetDto;
    private List<TransactionDto> transactions;

    public UserDto() {
    }

    public UserDto(String username, String password,
                   String email, Boolean admin, List<AccountDto> accounts, BudgetDto budgetDto, List<TransactionDto> transactions) {
        this.username = username;
        this.password = password;
        this.email = email;
        this.admin = admin;
        this.accounts = accounts;
        this.budgetDto = budgetDto;
        this.transactions = transactions;
    }

用户映射器：

@Mapper(componentModel = "spring")
public abstract class UserMapper {
    @Autowired
    EntityManager entityManager;

    public abstract UserDto toDto(User user);

    @Mapping(target="accounts", ignore=true)
    @Mapping(target="budget", ignore=true)
    @Mapping(target="transactions", ignore=true)
    public abstract User toEntity(UserDto userDto);

    @AfterMapping
    void afterToEntity(@MappingTarget User user, UserDto userDto){
        List<AccountDto> accountDtoList = userDto.getAccounts();
        List<Long> accountIds = accountDtoList.stream().map(AccountDto::getId).collect(Collectors.toList());

        List<Account> accounts = accountIds
                .stream()
                .map(id -> entityManager.find(Account.class, id))
                .collect(Collectors.toList());
        user.setAccounts(accounts);

        Long id = userDto.getBudgetDto().getId();
        Budget budget = entityManager.find(Budget.class, id);
        user.setBudget(budget);

        List<TransactionDto> transactionDtoList = userDto.getTransactions();
        List<Long> transactionIds = transactionDtoList.stream().map(TransactionDto::getId).collect(Collectors.toList());

        List<Transaction> transactions = transactionIds
                .stream()
                .map(t_id -> entityManager.find(Transaction.class, t_id))
                .collect(Collectors.toList());
        user.setTransactions(transactions);
    }
}

用户控制器：

@RestController
@RequestMapping("/user")
@CrossOrigin(origins = "http://localhost:4200")
public class UserController {
    @Autowired
    private UserService userService;
    @Autowired
    private UserMapper userMapper;

    @GetMapping("/test")
    public String hello(){
        return "Hello";
    }

    @GetMapping("/list")
    public List<UserDto> getAll() {
        List<User> categories = userService.findAll();
        return categories.stream()
                .map(userMapper::toDto)
                .collect(Collectors.toList());
    }

    @PostMapping("/create")
    public UserDto createUser(@Valid @RequestBody UserDto userDto) {
        User user = userMapper.toEntity(userDto);
        User userResult = userService.save(user);
        return userMapper.toDto(userResult);
    }

我尝试通过以下方式发出发布请求：

{“管理员”：“真”，“电子邮件”：“[e-mail]”，“密码”：“x”，“用户名”：“x”}

它返回：

{“时间戳”：“2019-06-02T14：15：51.825 + 0000”，“状态”：500，“错误”：“内部服务器错误”，“消息”：“没有可用消息”，“跟踪”：“ java.lang.NullPointerException

标签： javaspringrestdtomapstruct