我有一个基本的一对多的父子关系,就像Hibernate参考书的第21章中所述。
级联只从子到父(仅持久化级联,因为如果删除子项,我不想删除父项)。
当我将一个子项添加到父项并保存子项时,我遇到了TransientObjectException...
@Entity
public class Parent implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@OneToMany(mappedBy = "parent", orphanRemoval = true)
private List<Child> childs;
public List<Child> getChilds() {
return childs;
}
public void setChilds(List<Child> childs) {
this.childs = childs;
}
public void addChild(Child child) {
if (childs == null) childs = new ArrayList<Child>();
if (childs.add(child)) child.setParent(this);
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
@Entity
public class Child implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@ManyToOne(optional = false)
@Cascade( { PERSIST, MERGE, REFRESH, SAVE_UPDATE, REPLICATE, LOCK, DETACH })
private Parent parent;
public Parent getParent() {
return parent;
}
public void setParent(Parent parent) {
this.parent = parent;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
@Test
public void test() {
Parent parent = new Parent();
Child child = new Child();
parent.addChild(child);
genericDao.saveOrUpdate(child);
}
但是在执行saveOrUpdate时,我遇到了这个异常:
org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: Child
at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:244)
at org.hibernate.collection.AbstractPersistentCollection.getOrphans(AbstractPersistentCollection.java:911)
at org.hibernate.collection.PersistentBag.getOrphans(PersistentBag.java:143)
at org.hibernate.engine.CollectionEntry.getOrphans(CollectionEntry.java:373)
at org.hibernate.engine.Cascade.deleteOrphans(Cascade.java:471)
at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:455)
at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:362)
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:338)
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
at org.hibernate.engine.Cascade.cascade(Cascade.java:161)
at org.hibernate.event.def.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:476)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:354)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:677)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:669)
at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:252)
at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335)
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
at org.hibernate.engine.Cascade.cascade(Cascade.java:161)
at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:451)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:288)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:677)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:669)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:665)
我真的不明白为什么通过级联保存子项应该能够保存父项...有什么想法吗?
更新1 问题似乎与"orphanRemoval"有关,因为如果我在父项上注释它:
@OneToMany(mappedBy = "parent" /*, orphanRemoval = true */)
private List<Child> childs;
它有效!
它保留了子项,然后是父项。
但是当我从其父项中删除一个子项时,我真的需要通过级联删除孤儿。
更新2
我已经创建了一个JIRA问题:
http://opensource.atlassian.com/projects/hibernate/browse/HHH-5364
更新3
看起来已经修复了:-)
http://opensource.atlassian.com/projects/hibernate/browse/HHH-2269