是否可以在没有迭代的情况下加载具有所有惰性属性的对象？

Question

I have an object which has children, some of which loaded lazy some not. Now I have situation where I need a parent object to load with all the child at once. Is there quick way to do this without checking Hibernate.isInitialized() on all the properties?

Thank you

Answer 1

我将使用Hibernate.initialze(..) ，但是您也可以序列化对象（使用ObjectOutputStream或XMLEncoder 。序列化机制将迭代所有属性并将其初始化。您可以使用commons-lang SerializationUtils 。

Answer 2

How are you obtaining the object?

A general approach to this (it's often called 'hydration' of the objects) is to ask for a join fetch. That's where the ORM retrieves the data for the child objects at the same time as the data for the parent by using a join, and uses the data to eagerly initialize the children.

There are various ways to ask for a join fetch, mostly provider-specific, but you can write it into portable JPQL :

select p from Parent p join fetch p.children where ...

However, note that this will return each parent multiple times - as many as it has children. That's a bit weird, but it's how it works.

Answer 3

I agree with Tom, I use fetch joins to bring back child objects that I want initialized. As far as the query bringing back multiple Parent objects, I believe adding a "DISTINCT" clause should fix that.