SpringBoot JPA不需要@Transactional上的.save()吗? [英] SpringBoot JPA need no .save() on @Transactional?

问题描述

我有一个简短的问题:

我需要在@Transactional方法上进行repo.save(x)调用吗?

Do I need a repo.save(x) call on @Transactional methods?

我问是因为我没有保存就看到了数据库上的更改，并且没有阅读任何有关它的清晰文档.

I ask cause I see changes on my DB without save, and read no clear docs about it.

那么它是按预期工作的，还是只是(受欢迎的)意外行为?

So is it working as intended, or just a (welcome) unexpected behavior?

示例:

@Autowired
private UserRepo repo;

@Transactional  
@PutMapping
public Long put(@RequestBody User user)
{
  User u = repo.findOne(user.getId());
  u.setName("Paul");
  repo.save(u); // DO I NEED THIS LINE?
}

我只是不确定，所以也许有人可以对这个问题有所了解?

I'am just unsure about it, so maybe someone can shed some light on the subject?

推荐答案

如果您检索一个实体，例如在事务方法中使用findOne方法调用，则此实体已成为受管理的由持久性提供程序提供.

If you retrieve an entity, for example using the findOne method call within a transactional method it has become managed from that point by the persistence provider.

现在，如果您对该实体(实际上是代理对象)进行任何更改，则在提交事务后，无论调用save或update方法的事实如何，这些更改都将保留在数据库中.

Now if you make any changes to that entity (which is actually a proxy object), upon transaction commit, those changes will be persisted to the database, regardless of the fact of invoking the save or update methods.

save或persist.

请记住，如果您在特定实体上使用detach或evict方法，则可以防止在提交时进行任何更改.

Remember that you can prevent making any changes upon commit, if you use detach or evict methods on that particular entity before those changes occur.

这篇关于SpringBoot JPA不需要@Transactional上的.save()吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！