被驱逐的对象仍然在Hibernate中发布对数据库的更新 [英] Evicted object still issues updates to the database in Hibernate
问题描述
我在驱逐一个实体时遇到问题,但对其进行的更改仍然会更改数据库。这是我DAO中方法的一部分。
@Entity
public class Profile {
@Id
@GeneratedValue
私人长ID;
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name =PROFILE_ID)
@LazyCollection(LazyCollectionOption.FALSE)
private List< Avatar>化身;
}
在DAO方法中:
Profile profile = getProfile(...);
//从休眠中清除
currentSession.evict(profile);
profile.setId(null);
(Avatar a:profile.getAvatars()){
currentSession.evict(a);
a.setId(null);
}
currentSession.save(profile); //保存一份配置文件(不更新)
之前:
PUBLIC.PROFILE
ID,DOMAIN,STATUS
1,test,MEMBER
PUBLIC .AVATAR
ID,NAME,PROFILE_ID
1,main,1
after method
PUBLIC.PROFILE
ID,DOMAIN,STATUS
1,test,会员
2,test,会员
PUBLIC.AVATAR
ID,名称,简介_ID
1,主要,无效
2,main,2
正如你所看到的,AVATAR中的原始行现在有一个空外键。
为什么?这发生在使用Unitils和Spring 和的单元/集成测试中,这可能会影响Hibernate DAO的工作方式,也许。
一个内存中的H2数据库..添加行后
profile.setAvatars(new ArrayList<>(profile.getAvatars());
$ b $
$ b
所以我猜这个问题是Hibernate执行 List
,但是怎么会影响行为呢?
编辑:首先回答很蠢,因为 @LazyCollection(LazyCollectionOption.FALSE)
我可以重现和修复,但我无法理解实际发生的情况......
首先会发生什么情况(在调试器中侦察):
由于 avatars
集合是渴望的, profile.getAvatars()
完全填充,是一个Hibernat e集合(在我自己的测试中,它是一个 PersistentBag
)
当 profile
被驱逐出境,它的所有头像也被驱逐(至少在Hibernate 4.1.9 Final中)。
On currentSession.save(profile)
全部都非常棒,插入了一个新的 Profile
,并且还插入了一个新的 Avatar
。但在接下来的事务提交中,Hibernate决定去做着名的
update Avatar set profile_id = null where profile_id = 1;
: - (
接下来的修正:
我认为Hibernate惊讶地发现一个新实体已经有一个 PersistentBag
携带一个集合,所以我创建了一个简单的 ArrayList
,附加了当前的 Avatars
,并将它放入 profile
:
List< Avatar> avatars = new ArrayList< Avatar>( );
for(Avatar a:profile.getAvatars()){
currentSession.evict(a); //实际上无用但无害
a.setId(null);
avatars.add(a);
}
profile.setAvatars(avatars);
所以原因似乎是 PersistentBag
I have a problem where I evict an entity, but changes made to it will still change the database. This is part of the method in my DAO.
@Entity
public class Profile {
@Id
@GeneratedValue
private Long id;
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "PROFILE_ID")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Avatar> avatars;
...
}
In a DAO method:
Profile profile = getProfile(...);
// Clear from hibernate
currentSession.evict(profile);
profile.setId(null);
for (Avatar a : profile.getAvatars()) {
currentSession.evict(a);
a.setId(null);
}
currentSession.save(profile); // save a copy of Profile (not update)
before:
PUBLIC.PROFILE
ID, DOMAIN, STATUS
1, "test", "MEMBER"
PUBLIC.AVATAR
ID, NAME, PROFILE_ID
1, "main", 1
after method
PUBLIC.PROFILE
ID, DOMAIN, STATUS
1, "test", "MEMBER"
2, "test", "MEMBER"
PUBLIC.AVATAR
ID, NAME, PROFILE_ID
1, "main", null
2, "main", 2
So as you can see, the original row in AVATAR has now a null foreign key.
Why? This is happening in a unit / integration test using Unitils and Spring and this might influence how the Hibernate DAO works, maybe.
It's all in a in-memory H2 database..
After adding a line
profile.setAvatars(new ArrayList<>(profile.getAvatars());
it works ...
So I guess the problem was Hibernate's implementation of List
, but how could that affect the behavior??
EDIT : First answer was stupid because of @LazyCollection(LazyCollectionOption.FALSE)
I could reproduce and fix but I cannot understand what actually happens under the hood ...
First what happens (spyed under debugger):
As avatars
collection is eager, profile.getAvatars()
is fully populated and is a Hibernate collection (in my own tests, it is a PersistentBag
)
When profile
is evicted, all its avatars are also evicted (at least with Hibernate 4.1.9 Final).
On currentSession.save(profile)
all is marvelous, a new Profile
is inserted and also a new Avatar
. But on following transaction commit, Hibernate decides to do the famous update Avatar set profile_id = null where profile_id = 1;
:-(
Next the fix :
I supposed that Hibernate is surprised to find a new entity already having a PersistentBag
to carry a collection. So I created a simple ArrayList
, appended current Avatars
to it, and put it into profile
:
List<Avatar> avatars = new ArrayList<Avatar>();
for (Avatar a : profile.getAvatars()) {
currentSession.evict(a); // in fact useless but harmless
a.setId(null);
avatars.add(a);
}
profile.setAvatars(avatars);
And ... all is fine, Hibernate no longer emits the offending update !
So the cause seems to be a PersistentBag
in a new entity, but i cannot imagine what actually happens in Hibernate internals.
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