Relationship between OSIV & JPA Entity Listener @PreUpdate

Question

User user = userRepository.findOne(1);
user.age = user.age + 1; // user.age value modify
userService.updateUser(user);

@Transactional
class UserService {
   public void updateUser(User user) {
      productRepository.findByName("AAA"); // (1)
      userRepository.save(user); // (2)
   }
}

@Entity
@EntityListener(UserListener.class)
class User {...}

class UserListener{
   @PreUpdate
   public void onPreUpdate() { ... }
}

When OSIV = true, (1) line --> @PreUpdate called / (2) line --> @PreUpdate called

When OSIV = false, (1) line --> @PreUpdate not called / (2) line --> @PreUpdate called

Why does this happen? Why @preupdate called when (1) line executed?

Answer 1

Here is the JPA 2.0 specification:

The PreUpdate and PostUpdate callbacks occur before and after the database update operations to entity data respectively. These database operations may occur at the time the entity state is updated or they may occur at the time state is flushed to the database (which may be at the end of the transaction).

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Keep in mind that @PreUpdate it will always be triggered for all read/write transactions because of the FlushMode on read/write transactions and never on readonly transactions (because of FlushMode.NEVER)

Without OSIV

When you call updateUser , then you have a read/write transaction (the outer one) because of @Transactional.

Now, findByName is transactional but marked as readonly (by default all finders are readonly). The current transaction is suspended and a new readonly one is performed. That's why (1) line does not trigger @Preupdate.

After that, the current read/write transaction resumes (save is not readonly) and the @Preupdate is triggered.

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With OSIV

This case there is only one read/write transaction bound to the current request. findByName is executed in a read/write transaction, therefore (1) line does trigger @Preupdate