我在Hibernate参考书的第21章中有一个基本的一对多关系父/子
级联仅从子级到父级(持久级联,因为我不想删除父级,如果我删除子级)。
当我向父母添加一个孩子并保存孩子时,我有一个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saveOrUpdate上,我有这个例外:
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,因为保存孩子应该通过级联保存父母... 有什么想法吗?
更新1
这个问题似乎与“orphanRemoval”有关,因为如果我在父母身上发表评论:
@OneToMany(mappedBy = "parent" /*, orphanRemoval = true */)
private List<Child> childs;
它有效!
它拯救了孩子,然后是父母
但是当我从其父级中删除一个孩子时,我真的需要通过级联删除孤儿。
更新2
我创建了一个JIRA问题:
http://opensource.atlassian.com/projects/hibernate/browse/HHH-5364
更新3
它似乎是固定的:-)
http://opensource.atlassian.com/projects/hibernate/browse/HHH-2269
答案 0 :(得分:1)
这是Hibernate中的一个问题,现在已修复:
http://opensource.atlassian.com/projects/hibernate/browse/HHH-2269
答案 1 :(得分:0)
基本上你违反了约束。 db中与父项对应的行不存在,因此子项不能用于引用父项的外键关系。在为孩子做之前,在父母上添加对saveOrUpdate的调用。
(编辑)在重新格式化之前,我错过了关于级联的评论。我的回忆是,级联在上游不起作用;你仍然需要先保存父母。