我有以下3个模型：
模式 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<>();
}
模式二：客房预订：
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<>();
}
型号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;
}
这三者之间的关系如下：
预订 - RESERVATION_ID一对多 ->客房预订 - ROOM_RESERVATION_ID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，我收到以下错误：
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
我已经按照常见问题中的建议将级联类型更改为 ALL，但仍然收到相同的错误。请不要让它重复，因为我已经尝试了已经问过的此类问题的所有解决方案
请让我知道我犯了什么错误。谢谢
通过更改客人详细信息来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);
... save the transient instance before flushing :
com.model.GuestDetails.roomReservation -> com.model.RoomReservation
此异常清楚地表明RoomReservation包含在 GuestDetails 中，在数据库中不存在（很可能是id是null）。
通常，您可以通过以下任一方式解决此异常：
保存客房预订实体之前保存客人详细信息
或者为
@ManyToOneGuestDetail-->RoomReservation制作cascade = CascadeType.ALL（或至少{CascadeType.MERGE, CascadeType.PERSIST}）
但首先，我有几点要介绍：
不要在类中使用公共字段，这违反了封装概念。
当您具有双向关联时，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！
这可能是由不正确的事务语义引起的。
如果未在当前事务中获取引用的实例，则将其计为暂时性实例。
最简单的解决方案是将@Transactional添加到该方法中：
@Transactional
public void saveReservation(...) {
Reservation existingReservation = reservationRepository.findOne(reservationId);
Reservation reservation = reservationParser.createFromJson(reservationNode);
// ...
reservationRepository.save(existingReservation);
}
GuestDetails - 添加所需的 CasadeType：
@ManyToOne(fetch = FetchType.LAZY, cascade=CascadeType.ALL)
@JoinColumn(name = "ROOM_RESERVATION_ID")
public RoomReservation roomReservation;
房间预订 - 添加层叠类型：
@JsonIgnore
@ManyToOne(fetch = FetchType.LAZY, cascade=CascadeType.AL)
@JoinColumn(name = "RESERVATION_ID")
public Reservation reservation;
然后，您需要在使用for-each循环之前/之后保留数据。取决于你safe()方法。
Reservation reservation = reservationParser.createFromJson(reservationNode);
entityManager.persist(reservation);
然后保护它。告诉我你的结果。也许直接工作而无需更改/添加级联类型。
您可以保存从 JSON 获得的预留。JPA 将使用相同的 id 更新行。
您得到的错误是因为来宾详细信息仍然引用了更新的房间预订。如果您不想从 json 中保存整个预订，则必须设置正确的房间预订。
例如：
if(updatedRoomReservation != null){
roomReservation.guestDetails = updatedRoomReservation.guestDetails;
guestDetails.forEach(guestDetail -> guestDetail.roomReservation = roomReservation);
}
如果您使用的是 JPA 2.0，那么 OneToMany 的默认获取类型是 LAZY。如果在 lambda 之后，您的updatedRoomReservation为空（如您在 orElse 中设置的那样），则existingReservation.roomReservation.guestDetails永远不会被加载，并且将为空。
因此，当您保存existingReservation时，您会收到错误。