The spring data JPA repository.save method automatically saves all entities？-CodePudding

In the following code, why is user1 saved to the database? repository.save method automatically saves all entities？

@RestController
@RequestMapping("/test")
public class Test {

    @Autowired
    private UserRepository userRepository;

    @PostMapping("/test")
    public void test() {
        User user1 = userRepository.findById(1);
        user1.setPhone("1");

        User user2 = userRepository.findById(2);
        userRepository.save(user2);
    }
}

CodePudding user response：

The repository doesn't save the entities; instead, JPA is a "magic" system where changes to persistent entities are automatically saved when the transaction commits. Repositories using other persistence technologies do require explicit save operations for each object.

CodePudding user response：

Basically, it depends upon your transaction boundary, if you have an active non-readonly transaction and you are doing some modifications to managed (attached) entities, all the changes will be saved/persisted once transaction is committed. This is fundamental principle of JPA/Hibernate. Ideally attached entities should not be modified if changes are not required.