Hibernate:拉取所有惰性集合的最佳实践 [英] Hibernate: best practice to pull all lazy collections

问题描述

我有什么:

@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
}

有什么问题:

问题是我无法在会话关闭后拉延迟收集.但是我也不能在 proceed 方法中关闭会话.

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.

什么解决方案(粗略的解决方案):

a) 在会话关闭之前，强制休眠拉取惰性集合

a) Before session is closed, force hibernate to pull lazy collections

entity.getAddresses().size();
entity.getPersons().size();

....

b) 也许更优雅的方式是使用 @Fetch(FetchMode.SUBSELECT) 注释

b) Maybe more ellegant way is to use @Fetch(FetchMode.SUBSELECT) annotation

问题:

什么是最佳实践/常用方法/更优雅的方法?意味着将我的对象转换为 JSON.

What is a best practice/common way/more ellegant way to do it? Means convert my object to JSON.

推荐答案

在 @Transactional 中使用 Hibernate.initialize() 来初始化惰性对象.

Use Hibernate.initialize() within @Transactional to initialize lazy objects.

 start Transaction 
      Hibernate.initialize(entity.getAddresses());
      Hibernate.initialize(entity.getPersons());
 end Transaction 

现在在事务之外，您可以获得惰性对象.

Now out side of the Transaction you are able to get lazy objects.

entity.getAddresses().size();
entity.getPersons().size();

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