在休眠JPA的getReference()之后不使用setter发出select的情况下无法更新 [英] cannot update without issuing select on using setter after getReference() of hibernate JPA

问题描述

我有以下方法-

 @Transactional
 public void savethis(){
    EntityObject t = entityManagerTreasury.getReference(EntityObject.class, 1);
    t.setAction("abc");
 }

现在，符合以下答案- https://stackoverflow.com/a/1608621/4881766

Now, going in line with the following answer - https://stackoverflow.com/a/1608621/4881766

我应该只会在我的sql日志中看到一个更新查询.

I should be only seeing an update query in my sql logs.

但是我观察到的行为如下-

However the behaviour i've observed is as follows -

1. 提供代码-选择然后更新
2. 评论t.setAction("abc");行-没有选择也没有更新
3. 用find()替换getReference()-选择然后更新

我期望的行为是，如果我在代理上使用任何getter，则应该发出选择，但是当仅使用setter时，我希望在方法末尾通过更新和更新来提交更改.没有选择发布.

The behaviour i was expecting was that if i use any getter on the proxy, then a select should be issued, but when only using a setter, i wanted the changes to be committed at the end of the method with an update and no select being issued.

结果是，无论我对代理对象，getter或setter做什么，它都会发出选择.

Turns out, no matter what i do with the proxy object, getter or setter, it issues a select.

我想更新给定ID的实体的选定字段. 如果有任何方法可以在不编写jpql或本机查询的情况下更新我想要的任何字段，我将不胜感激.

I want to update selected fields of an entity for a given id. If there is any way to update any fields that i want without writing jpql or native query, I'd really appreciate it.

提前谢谢！

推荐答案

来自

获取一个实例，其状态可能会延迟获取.

Get an instance, whose state may be lazily fetched.

因此，在entityManagerTreasury.getReference之后不会发出选择.

Therefore, after entityManagerTreasury.getReference no select is issued.

仅在t.setAction("abc")之后，如果尚未获取实体状态，则发出选择以获取状态.

Only after t.setAction("abc"), if the entity state is not already fetched, a select is issued to fetch the state.

重点是:除非获取实体状态，否则实体管理器无法保存实体的状态.因此，除非您使用JPQL，否则您不能跳过先前的选择.

The point is: the entity manager cannot save the state of an entity unless the entity state is fetched. Therefore you cannot skip the prior select, unless you use JPQL.

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