我有以下 3 个模型:

模型 1:预订

    @Entity
    public class Reservation  {
    
        public static final long NOT_FOUND = -1L;
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        public Long id;
        
        @OneToMany(mappedBy = "reservation", cascade = CascadeType.ALL, orphanRemoval = true)
        public List<RoomReservation> roomReservations = new ArrayList<>();
}

模型 2:房间预订:

 public class RoomReservation extends{
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        public Long id;
    
        @JsonIgnore
        @ManyToOne(fetch = FetchType.LAZY)
        @JoinColumn(name = "RESERVATION_ID")
        public Reservation reservation;
    
        @OneToMany(mappedBy = "roomReservation", cascade = CascadeType.ALL, orphanRemoval = true)
        public List<GuestDetails> guestDetails = new ArrayList<>();
    }

模型 3:客人详细信息:

public class GuestDetails {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Long id;

    public Long guestId;

    @JsonIgnore
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "ROOM_RESERVATION_ID")
    public RoomReservation roomReservation;

    public Boolean isPrimary;

    @Transient
    public Guest guest;

}

三者的关系如下:

预订——RESERVATION_ID 上的一对多——> 房间预订——ROOM_RESERVATION_ID 上的一对多——> 客人详细信息

我正在获取预订对象并尝试更新客人详细信息时出现以下错误:

org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : com.model.GuestDetails.roomReservation -> com.model.RoomReservation
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1760)
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
    at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:82)
    at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
... 73 common frames omitted

我已按照常见问题中的建议将 cascadeType 更改为 ALL，但仍然出现相同的错误。请不要将其重复，因为我已经尝试了与已提出的此类问题相关的所有解决方案

请让我知道我在做什么错误。谢谢

通过更改 GuestDetails 保存预订对象的代码:

Reservation existingReservation = reservationRepository.findOne(reservationId);
Reservation reservation = reservationParser.createFromJson(reservationNode);
existingReservation.roomReservations.forEach(roomReservation -> {
                    RoomReservation updatedRoomReservation = reservation.roomReservations.stream().filter(newRoomReservation -> Objects.equals(roomReservation.id, newRoomReservation.savedReservationId)).findFirst().orElse(null);
                    if(updatedRoomReservation != null){
                        roomReservation.guestDetails = updatedRoomReservation.guestDetails;
                    }
                });
reservationRepository.save(existingReservation);

最佳答案

... save the transient instance before flushing : 
    com.model.GuestDetails.roomReservation -> com.model.RoomReservation

此异常清楚地表明 GuestDetails 中包含的 RoomReservation 不存在于数据库中(很可能它的 id 是 空).

一般，您可以通过以下方式解决此异常:

• 在保存 GuestDetails 之前先保存 RoomReservation 实体

• 或者为 @ManyToOne 创建 cascade = CascadeType.ALL(或至少 {CascadeType.MERGE, CascadeType.PERSIST}) > GuestDetail-->RoomReservation

但首先，我有几点要说明:

• 不要在你的类中使用公共(public)字段，这违反了the encapsulation concept .

• 虽然您拥有双向关联，但您可以在 Setter 方法中设置关联的另一端。

对于您的情况，您应该更改 RoomReservation 类:

public class RoomReservation{

    //..... other lines of code

    @OneToMany(mappedBy = "roomReservation", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<GuestDetails> guestDetails = new ArrayList<>();

    public void setGuestDetails(List<GuestDetails> guestDetails) {

           this.guestDetails.clear();

           // Assuming that by passing null or empty arrays, means that you want to delete
           // all GuestDetails from this RoomReservation entity
           if (guestDetails == null || guestDetails.isEmpty()){
               return;
           }

           guestDetails.forEach(g -> g.setRoomReservation(this));
           this.guestDetails.addAll(guestDetails);
    }

    public List<GuestDetails> getGuestDetails() {
        // Expose immutable collection to outside world  
        return Collections.unmodifiableList(guestDetails);
    }

    // You may add more methods to add/remove from [guestDetails] collection
}

保存预订:

Reservation existingReservation = reservationRepository.findOne(reservationId);
Reservation reservation = reservationParser.createFromJson(reservationNode);
existingReservation.roomReservations.forEach(roomReservation -> {
                    Optional<RoomReservation> updatedRoomReservation = reservation.roomReservations.stream().filter(newRoomReservation -> Objects.equals(roomReservation.id, newRoomReservation.savedReservationId)).findFirst();
                    if(updatedRoomReservation.isPresent()){
                        // roomReservation already exists in the database, so we don't need to save it or use `Cascade` property
                        roomReservation.setGuestDetails( updatedRoomReservation.get().getGuestDetails());
                    }
                });
reservationRepository.save(existingReservation);

希望对您有所帮助!

关于java - 对象引用未保存的 transient 实例 - 在刷新 : Spring Data JPA 之前保存 transient 实例，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46848188/