無法創建其中兩個屬性是另一個物體的Id和另一個物體的Id的ArrayList的物體-有解無憂

我是 Spring Boot 的 JPA 概念的新手，所以在決定如何匯入另一個物體的 ID 和另一個物體的 ArrayList 時需要你的幫助。我想創建一個板，提供一個帳戶的 ID 和帳戶 ID 的 ArrayList。以下是我的賬戶和董事會物體：

@Entity(name = "Account")
@Table(name = "account", uniqueConstraints = {@UniqueConstraint(name = "account_email_unique", columnNames = "email")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "account_id")
    private Integer accountId;

    @JsonIgnore
    @OneToMany(targetEntity = Board.class, mappedBy = "boardOwnerId")
    private Set<Board> boardSet = new HashSet<>();

    @JsonIgnore
    @ManyToMany(mappedBy = "boardMembers")
    private Set<Board> boards = new HashSet<>();


@Entity(name = "Board")
@Table(name = "board", uniqueConstraints = {@UniqueConstraint(name = "board_name_unique", columnNames = "name")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Board {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "board_id")
    private Integer boardId;

    @ManyToOne(targetEntity = Account.class, cascade = CascadeType.ALL)
    @JoinColumn(name = "account_id", referencedColumnName = "account_id")
    private Account boardOwnerId;

    @ManyToMany
    @JoinTable(name = "board_member", joinColumns = @JoinColumn(name = "board_id"), inverseJoinColumns =
    @JoinColumn(name = "account_id"))
    private Set<Account> boardMembers = new HashSet<>();



@Repository
public interface BoardRepository extends JpaRepository<Board, Integer> {
}


@RestController
@RequestMapping("/boards")
public class BoardController {
    private final BoardService boardService;

    @Autowired
    public BoardController(BoardService boardService) {
        this.boardService = boardService;
    }

    @PostMapping("/create-board")
    ResponseEntity<BoardDtoResponse> createBoard(@Valid @RequestBody BoardDto boardDto) {
        return new ResponseEntity<>(boardService.createBoard(boardDto), HttpStatus.CREATED);
    }
}


@Service
public class BoardServiceImpl implements BoardService {
    private final BoardRepository boardRepository;
    private final ModelMapper modelMapper;

    @Autowired
    public BoardServiceImpl(BoardRepository boardRepository) {
        this.boardRepository = boardRepository;
        modelMapper = new ModelMapper();
    }

    @Override
    public BoardDtoResponse createBoard(BoardDto boardDto) {
        Board boardToSave = modelMapper.map(boardDto, Board.class);

        Board newBoard =  boardRepository.save(boardToSave);

        return modelMapper.map(newBoard, BoardDtoResponse.class);
    }
}

我可以成功創建一個帳戶，但是當我想創建一個董事會并傳遞 boardOwnerId 和 membersIds 時，它會創建一個董事會，但是 boardOwnerId 和 membersIds 設定為 null。

這是通過郵遞員提出的請求：

在此先感謝您的時間！

uj5u.com熱心網友回復：

據我所見，您應該更改兩個映射的兩個物體之間的映射。讓我解釋：

對于板所有者 (@OneToMany) 的映射，請嘗試僅維護一個注釋并從 Board 物體中洗掉帶有 @ManyToOne 的屬性。此外，更改 @OneToMany 注釋的屬性值并添加具有下一個值的 @JoinColumn：

@Entity(name = "Account")
@Table(name = "account", uniqueConstraints = {@UniqueConstraint(name = "account_email_unique", columnNames = "email")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "account_id")
    private Integer accountId;

    @JsonIgnore
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, orphanRemoval = true)
    @JoinColumn(name = "boardOwnerId")
    private Set<Board> boardSet = new HashSet<>();
    ...


@Entity(name = "Board")
@Table(name = "board", uniqueConstraints = {@UniqueConstraint(name = "board_name_unique", columnNames = "name")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Board {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "board_id")
    private Integer boardId;
    ...

這稱為一對多單向映射 ( https://www.bezkoder.com/jpa-one-to-many-unidirectional/ )。

另一方面，您可以嘗試僅在 Board 物體上維護 @ManyToOne 注釋，但從具有下一個屬性值的 Account 物體中洗掉帶有 @OneToMany 注釋的屬性：

@Entity(name = "Account")
@Table(name = "account", uniqueConstraints = {@UniqueConstraint(name = "account_email_unique", columnNames = "email")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "account_id")
    private Integer accountId;
    ...


@Entity(name = "Board")
@Table(name = "board", uniqueConstraints = {@UniqueConstraint(name = "board_name_unique", columnNames = "name")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Board {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "board_id")
    private Integer boardId;

    @JsonIgnore
    @ManyToOne(fetch = FetchType.LAZY, optional = false) 
    @JoinColumn(name = "account_id", nullable = false)
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Account boardOwnerId;
    ...

這稱為默認的一對多映射 ( https://www.bezkoder.com/jpa-one-to-many/ )。

在任何情況下，您都會看到您只需為一對多映射實作兩種型別的注釋中的一種。

最后，對于 @ManyToMany 映射，嘗試下一個實作（添加 fetch 和 cascade 屬性值）：

@Entity(name = "Account")
@Table(name = "account", uniqueConstraints = {@UniqueConstraint(name = "account_email_unique", columnNames = "email")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Account {
    ...

    @ManyToMany(fetch = FetchType.LAZY,
      cascade = {
          CascadeType.PERSIST,
          CascadeType.MERGE
      },
      mappedBy = "boardMembers")
    @JsonIgnore
    private Set<Board> boards = new HashSet<>();


@Entity(name = "Board")
@Table(name = "board", uniqueConstraints = {@UniqueConstraint(name = "board_name_unique", columnNames = "name")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Board {
    ...

    @ManyToMany(fetch = FetchType.LAZY,
      cascade = {
          CascadeType.PERSIST,
          CascadeType.MERGE
      })
    @JoinTable(name = "board_member", joinColumns = @JoinColumn(name = "board_id"), inverseJoinColumns =
    @JoinColumn(name = "account_id"))
    private Set<Account> boardMembers = new HashSet<>();

您可以在此處找到此實作設計：https ://www.bezkoder.com/jpa-many-to-many/

uj5u.com熱心網友回復：

問題是物體沒有與 dto 正確映射。解決方案是顯式映射加上 Gescof 的答案。

在這里我找到了關于顯式映射的資訊：ModelMapper mapping the wrong id

更改服務類中的代碼：

@Service
public class BoardServiceImpl implements BoardService {
    private final BoardRepository boardRepository;
    private final ModelMapper modelMapper;

    @Autowired
    public BoardServiceImpl(BoardRepository boardRepository) {
        this.boardRepository = boardRepository;
        modelMapper = new ModelMapper();
        modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.LOOSE);
    }


    @Override
    public BoardDtoResponse createBoard(BoardDto boardDto) {
        Board boardToSave = modelMapper.map(boardDto, Board.class);

        Board newBoard =  boardRepository.save(boardToSave);

        return modelMapper.map(newBoard, BoardDtoResponse.class);
    }
}

物體類中的更改代碼：

@Entity(name = "Account")
@Table(name = "account", uniqueConstraints = {@UniqueConstraint(name = "account_email_unique", columnNames = "email")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "account_id")
    private Integer accountId;

    @JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY,
            cascade = {
                    CascadeType.PERSIST,
                    CascadeType.MERGE
            },
            mappedBy = "boardMembers")
    private Set<Board> boards = new HashSet<>();


@Entity(name = "Board")
@Table(name = "board", uniqueConstraints = {@UniqueConstraint(name = "board_name_unique", columnNames = "name")})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class Board {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "board_id")
    private Integer boardId;

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "account_id", nullable = false)
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Account boardOwnerId;

    @ManyToMany(fetch = FetchType.LAZY,
            cascade = {
                    CascadeType.PERSIST,
                    CascadeType.MERGE
            })
    @JoinTable(name = "board_member", joinColumns = @JoinColumn(name = "board_id"), inverseJoinColumns =
    @JoinColumn(name = "account_id"))
    private Set<Account> boardMembers = new HashSet<>();

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