如何創建多對一列的獲取請求？

我目前已經製作了一個用於事件系統的彈簧啟動項目。在預訂課程的模型中，我有兩個對象，一個是事件，另一個是用戶。現在我想創建一個 get 請求，允許我分別獲取單個用戶的所有預訂和單個事件的所有預訂。我設法創建了其他請求，這些請求正在獲取所有預訂並通過預訂 ID 進行預訂。

現在，如果我嘗試創建任何類型的實現，它要么給我一個空指針錯誤，要么告訴我表關係“預訂”不存在。請讓我知道是否可以編寫這樣的獲取請求。謝謝

模型：

@Id
@SequenceGenerator(
        name = "booking_sequence",
        sequenceName = "booking_sequence",
        allocationSize = 1
)
@GeneratedValue(
        strategy = GenerationType.SEQUENCE,
        generator = "booking_sequence"
)
private Long id;

@ManyToOne
@JoinColumn(
        name = "event_id",
        referencedColumnName = "id"
)
private Event event;

@ManyToOne
@JoinColumn(
        name = "user_id",
        referencedColumnName = "id"
)
private User user;

private Integer tickets;
@Transient
private Integer amount;

存儲庫：

@Repository
public interface BookingRepository extends JpaRepository<Booking, Long > {
    @Query
    Optional<Booking> findBookingById(Long id);
}

服務：

@Autowired
public BookingService(BookingRepository bookingRepository) {
    this.bookingRepository = bookingRepository;
}

public List<Booking> getBookingList() {
    return bookingRepository.findAll();
}

public Booking getSingleBooking(Long bookingId) {
    return bookingRepository.findBookingById(bookingId).orElseThrow();
}

控制器：

@GetMapping
public List<Booking> getBookings() {
    return bookingService.getBookingList();
}

@GetMapping(path = "{bookingId}")
public Booking getSingleBooking(@PathVariable("bookingId") Long bookingId) {
    return bookingService.getSingleBooking(bookingId);}

@GetMapping(path = "/user/{userId}")
public List<Booking> getUserBookings(@PathVariable("userId") Long userId) {
    return bookingService.getBookingByUser(userId);}

@GetMapping(path = "/event/{eventId}")
public List<Booking> getEventBookings(@PathVariable("eventId") Long eventId) {
    return bookingService.getBookingForEvent(eventId);}