我正在嘗試保存一個(gè)通過 OneToMany 關(guān)系與“志愿者”對象相關(guān)的“用戶”對象。當(dāng)我嘗試保存它時(shí)，它僅在我為這兩個(gè)對象提供主要 ID 時(shí)才有效。但是，我需要的是保存實(shí)體并讓數(shù)據(jù)庫通過 autoIncrement 指定 ID。我不確定我該怎么做，或者即使有可能。有效的 Json 映射：{ "id":8, "userName": "user8", "password": "pass1234", "volunteersId": 6, "volunteers": [{ "id":6, "committeesId": 2, "outreachDate": "2019-12-07", "usersId": 8 }]}我需要的 Json 映射（但不會工作）：{ "userName": "user8", "password": "pass1234", "volunteersId": 6, "volunteers": [{ "committeesId": 2, "outreachDate": "2019-12-07", }]}所以我在想也許有一種方法可以連接外鍵，這樣我就不必顯式添加自動增量 ID（usersId、volunteersId）。用戶控制器：@Controllerpublic class UserController { @RequestMapping(value = "/v1/users", method = RequestMethod.POST) public ResponseEntity<Object> saveUsers( @RequestBody UserEntity request){ try { return ResponseEntity.ok(userService.saveUser(request)); } catch (Exception e) { e.printStackTrace(); return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build(); } }}用戶服務(wù)：@Servicepublic class UserService { @Autowired private UserRepository userRepository; public Page<UserEntity> saveUser(UserEntity user){ userRepository.save(user); Pageable pageable = PageRequest.of(0, 10, Sort.by("id").descending()); return userRepository.findAll(pageable); }}用戶存儲庫：public interface UserRepository extends JpaRepository<UserEntity, Long> { public List<UserEntity> findAllByOrderByIdAsc(); public List<UserEntity> findAllByOrderByIdDesc(); public Page<UserEntity> findByUserNameContaining(String userName, Pageable pageable);}
2 回答
墨色風(fēng)雨
TA貢獻(xiàn)1853條經(jīng)驗(yàn) 獲得超6個(gè)贊
您需要在 @id 旁邊添加 @GeneratedValue 注釋
@Id
@GeneratedValue(strategy = GenerationType.selectOne)
private long id;
在序列的情況下，您需要添加一個(gè)額外的注釋
@Id
@SequenceGenerator(name = "customName", sequenceName = "sequenceNameInDatabase")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator="customName")
private long id;
慕田峪9158850
TA貢獻(xiàn)1794條經(jīng)驗(yàn) 獲得超8個(gè)贊
這將使主 ID 生成自動
@Entity
@Table(name = "user")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
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