Hibernate:拉取所有懒惰集合的最佳实践 [英] Hibernate: best practice to pull all lazy collections
问题描述
@Entity
public class MyEntity {
@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY,orphanRemoval = true)
@JoinColumn(name =myentiy_id)
private List< Address> addreses;
@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY,orphanRemoval = true)
@JoinColumn(name =myentiy_id)
private List< Person>者;
....
}
public void handle(){
Session session = createNewSession();
MyEntity entity =(MyEntity)session.get(MyEntity.class,entityId);
继续(会话); // FLUSH,COMMIT,CLOSE会话!
Utils.objectToJson(entity); // TROUBLES,因为它不能转换成json懒惰集合
}
问题所在:
问题在于会话关闭后,我无法拉取懒惰集合。但是我也不能在 proceed 方法中关闭会话。 b
$ b
什么是解决方案(粗略解决方案): p> a)在session关闭之前,强制hibernate拉取懒惰的集合
entity.getAddresses()。size();
entity.getPersons()。size();
....
b)也许更优雅的方式是使用 @Fetch(FetchMode.SUBSELECT)
注释
问题:
什么是最佳做法/常用方式/更优雅的方式?意味着将我的对象转换为JSON。
使用 Hibernate.initialize()
@Transactional
中初始化lazy对象。 start事务
Hibernate.initialize(entity.getAddresses());
Hibernate.initialize(entity.getPersons());
结束事务
现在在事务处理的外面,您可以获得惰性对象。
entity.getAddresses()。size();
entity.getPersons()。size();
What I have:
@Entity
public class MyEntity {
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, orphanRemoval = true)
@JoinColumn(name = "myentiy_id")
private List<Address> addreses;
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, orphanRemoval = true)
@JoinColumn(name = "myentiy_id")
private List<Person> persons;
//....
}
public void handle() {
Session session = createNewSession();
MyEntity entity = (MyEntity) session.get(MyEntity.class, entityId);
proceed(session); // FLUSH, COMMIT, CLOSE session!
Utils.objectToJson(entity); //TROUBLES, because it can't convert to json lazy collections
}
What a problem:
The problem is that I can't pull lazy collection after session has been closed. But I also can't not close a session in proceed method.
What a solution (coarse solution):
a) Before session is closed, force hibernate to pull lazy collections
entity.getAddresses().size();
entity.getPersons().size();
....
b) Maybe more ellegant way is to use @Fetch(FetchMode.SUBSELECT)
annotation
Question:
What is a best practice/common way/more ellegant way to do it? Means convert my object to JSON.
Use Hibernate.initialize()
within @Transactional
to initialize lazy objects.
start Transaction
Hibernate.initialize(entity.getAddresses());
Hibernate.initialize(entity.getPersons());
end Transaction
Now out side of the Transaction you are able to get lazy objects.
entity.getAddresses().size();
entity.getPersons().size();
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