Hibernate在级联所有保存时不生成子ID
[英]Hibernate not generating child id on cascade all save
问题描述
Parent Class: 
家长班：
@Entity
@Table(name = "****")
@Audited
public class Ship
{
@Id
@Column(name = "id")
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "uuid")
private String id;
@OneToMany(mappedBy = "associatedShip", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<ShipLoadlineInformation> loadlineInformation = new ArrayList<ShipLoadlineInformation>(0);
.. with other fields constructors, getters and setters.
}
Child class: 子班：
@Entity
@Table(name = "*********")
@Audited
public class ShipLoadlineInformation
{
@Id
@Column(name = "id")
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "uuid")
private String id;
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "ASSOCIATED_SHIP")
private Ship associatedShip;
.. with other fields, constructors, getter and setters
}
I am saving it in my DAO as follows: 我将其保存在我的DAO中，如下所示：
this.sessionFactory.getCurrentSession().save(ship);
When i try to save the object ship its giving me following error: 当我尝试保存对象时，它会给我以下错误：
org.hibernate.NonUniqueObjectException: A different object with the same identifier value was already associated with the session : [com.tms.model.transportMode.ShipLoadlineInformation#] at org.hibernate.engine.internal.StatefulPersistenceContext.checkUniqueness(StatefulPersistenceContext.java:618) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final] at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:301) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final] at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:244) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final] at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:109) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final] at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90) ~[hibernate
When debugging it, found out that the id for the parent class is getting generated. 在调试它时，发现正在生成父类的ID。 But the id for child class is not being generated. 但是未生成子类的ID。
I think this is the cause. 我认为这是原因。 Correct me if i am wrong. 如果我错了请纠正我。
Any help is appreciated. 任何帮助表示赞赏。
Thanks. 谢谢。
1 个解决方案
解决方案1
1 已采纳 2016-02-10 16:36:00
This error can occur when detached ShipLoadlineInformation instances are contained in the Ship.loadlineInformation collection. 当ShipLoadlineInformation实例包含在Ship.loadlineInformation集合中时，可能会发生此错误。 This way save action is cascaded to them when you save ship . 当您保存ship时，这种save动作被级联到他们身上。
The easiest way to get around it is to merge the ship (thus cascading merge operation to loadlineInformation as well). 解决它的最简单方法是合并船（因此也将层叠操作merge到loadlineInformation ）。
So, in your DAO replace: 因此，在您的DAO中替换：
this.sessionFactory.getCurrentSession().save(ship)
with: 与：
ship = this.sessionFactory.getCurrentSession().merge(ship)
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