Hibernate EntityManager:删除引用的实体不工作 [英] Hibernate EntityManager: remove referenced entity not working
问题描述
@ManyToOne
) - 然而,Hibernate不会删除任何东西 - 在调用 em.remove
一切都保持不变。 我有5个实体 E1 - E5
),像这样引用实体( E6
)
@Entity
public class EX {
@OneToMany(mappedBy =eX,fetch = FetchType.EAGER,cascade = {CascadeType。 PERSIST,CascadeType.REMOVE})
private Set< E6> e6s;
}
E6
本身有 @ManyToOne
关系:
public class E6 {
@ManyToOne(可选= false)
私人E1 e1;
@ManyToOne(可选= false)
私人E2 e2;
@ManyToOne(可选= false)
私人E3 e3;
@ManyToOne(可选= false)
私人E4 e4;
@ManyToOne(可选= false)
私人E5 e5;
(留下ids,附加栏等等)
每当我调用 em.remove(instanceOfE6)
时,只需 nothing 发生。我添加了Hibernate SQL-Output,并且看不到执行 DELETE
Query的单个尝试。
发生在ajax请求和新鲜 EntityManager中,我在删除之前添加了对合并的调用,导致otherwhise获得实体非托管异常:
em.remove(em.merge(instanceOfE6));
但没有。状态保持不变。
所以我试着添加一个 @PreRemove
方法来清除所有关系...方法从来没有被调用过。
我尝试了各种级联操作(包括 Cascade.ALL
) - 我需要的只是删除并坚持下去,那也应该是一样的。
我想过使用原生的Delete语句(每个实体都有一个代理ID,所以很可能会起作用) - 但因为所有事情都是在AJAX调用中发生的,所以我不想使用它,因为我希望更新持久缓存而不必重新获取每个涉及到的实体......
任何想法?
如果您需要更多资源,请给我留言。
我也尝试从所有关系中删除实体(对象明智),并调用 em.merge()
在剩下的其中一个实体上,希望hibernate能够鞭the未链接的实体 - 没有运气。
正如我所提到的,删除应该发生在ajax请求中。因此,简单的调用
em.remove(instanceOfE6);
导致 java.lang.IllegalArgumentException:删除分离的实例 code>异常。所以,我尝试了使用merge的方法:
em.remove(em.merge(instanceOfE6));
没有产生错误 - 但简单的行不通。我启用了这个帖子中提到的hibernate的跟踪日志记录: JPA / Hibernate删除实体有时候无法正常工作来找出问题所在,实际上,试图删除实体导致:
TRACE [org ... DefaultPersistEventListener]取消调度实体删除...
显然,要删除的实体是仍然连接到其他实体,这导致了休眠中止删除的问题,所以我试图在删除之前删除关系。
正如您从 E6
的例子中看到的,我使用了 @ManyToOne(可选= false)
,这意味着我无法将外向引用设置为null,否则在调用 merge
时会导致异常。
我第一次尝试清理关系只是清理集合,因为我认为清理我想要删除的实体的传出关系不是必需的。它不是,但稍后我会详细介绍这一点:
所以,现在的代码看起来像
instanceOfE6.getE1()getE6s()除去(instanceOfE6)。;
instanceOfE6.getE2()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE3()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE4()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE5()。getE6s()。remove(instanceOfE6);
em.remove(em.merge(instanceOfE6));
同样的问题:删除中止。我错过了一个显而易见的事实,即调用 merge
willc。恢复我刚删除的集合中的条目,因为instanceOfE6仍然不可空 - 对其他实体的引用。因此删除再次被中止。
最后解决c。在删除引用和最终删除之前做了合并:
if(!em.contains(instanceOfE6)){
instanceOfE6 = em.merge(instanceOfE6);
}
instanceOfE6.getE1()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE2()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE3()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE4()。getE6s()。remove(instanceOfE6);
instanceOfE6.getE5()。getE6s()。remove(instanceOfE6);
em.remove(instanceOfE6);
我不太确定是否解释了所有内容100%准确,但至少我可以通过来回更改代码来重现和修复问题。
I'm currenetly trying hard to delete an entity, that is involved in various relations (Only @ManyToOne
) - However, Hibernate does not delete anything - after calling em.remove
everything remains unchanged.
I have 5 entities (E1 - E5
), referencing the entity (E6
) in question like this:
@Entity
public class EX {
@OneToMany(mappedBy = "eX", fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.REMOVE })
private Set<E6> e6s;
}
E6
itself has the reverse @ManyToOne
Relations:
public class E6{
@ManyToOne(optional = false)
private E1 e1;
@ManyToOne(optional = false)
private E2 e2;
@ManyToOne(optional = false)
private E3 e3;
@ManyToOne(optional = false)
private E4 e4;
@ManyToOne(optional = false)
private E5 e5;
}
(left out ids, additional columns etc...)
Whenever I call em.remove(instanceOfE6)
, simply nothing happens. I added Hibernate SQL-Output and cannot see a single attempt of executing a DELETE
Query.
Since the deletion can happen from an ajax request and a fresh EntityManager, I added a call to merge before the deletion, cause otherwhise I get an Entity unmanaged Exception:
em.remove(em.merge(instanceOfE6));
But nothing. State remains unchanged.
So I tried to add an @PreRemove
Method to clear all the relations before removing the entity... Method gets never called.
I tried various Cascade Operations (Including Cascade.ALL
) - but since all I need is remove and persist, that should be working as well.
I thought about using a native Delete Statement (each entity has a surrogate id, so that would most likely work) - but since everything happens from within an AJAX-call, I don't want to use that, cause I want to have the Persistence-Cache updated without re-fetching every involved Entity...
Any ideas?
If you need more source, just drop me a comment.
I also tried to remove the entity in question from ALL relations (object wise), and call em.merge()
on one of the remaining entities, hoping that hibernate will whipe the unlinked entity - no luck.
I figured out the problem(s) - Actual there have been two of them: (Leaving this here, if somebody stumbles across a similar issue)
As I mentioned, the deletion should have happened in an ajax request. Therefore, simple calling
em.remove(instanceOfE6);
resulted in an java.lang.IllegalArgumentException: Removing a detached instance
exception. So, I tried the approach using merge:
em.remove(em.merge(instanceOfE6));
which did not produce an error - but simple didn't work. I enabled trace-logging for hibernate as mentioned in this post: JPA/Hibernate remove entity sometimes not working to figure out what went wrong, and indeed, trying to remove the entity resulted in:
TRACE [org...DefaultPersistEventListener] un-scheduling entity deletion ...
Obviously the entity to remove is still connected to other entities, which lead to the problem that hibernate aborted the deletion, so i tried to remove the relations before deletion.
As you can see from the example of E6
, I used @ManyToOne(optional = false)
, which means I cannot set the outgoing references to null, or it will cause exceptions when calling merge
.
My first attempt to clean the relations was only "cleaning the sets", because I assumed that cleaning the outgoing relations of the entity I want to delete is not required. It is not, but i'll outline this in detail a little later:
So, the code now looked like
instanceOfE6.getE1().getE6s().remove(instanceOfE6);
instanceOfE6.getE2().getE6s().remove(instanceOfE6);
instanceOfE6.getE3().getE6s().remove(instanceOfE6);
instanceOfE6.getE4().getE6s().remove(instanceOfE6);
instanceOfE6.getE5().getE6s().remove(instanceOfE6);
em.remove(em.merge(instanceOfE6));
Same issue: deletion aborted. I missed the obvious fact, that calling merge
will ofc. restore the entries inside the sets i just removed, because instanceOfE6 STILL had it's not nullable-references on the other entities. Therefore deletion was aborted again.
Finally the solution ofc. was to do the the merge before removing the references and the final deletion:
if (!em.contains(instanceOfE6)){
instanceOfE6 = em.merge(instanceOfE6);
}
instanceOfE6.getE1().getE6s().remove(instanceOfE6);
instanceOfE6.getE2().getE6s().remove(instanceOfE6);
instanceOfE6.getE3().getE6s().remove(instanceOfE6);
instanceOfE6.getE4().getE6s().remove(instanceOfE6);
instanceOfE6.getE5().getE6s().remove(instanceOfE6);
em.remove(instanceOfE6);
I'm not quite sure if I explained everything 100% accurate, but at least I can reproduce and fix the Issue by changing the code back and forth.
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