Object get updated in database automatically

Question

I'm using Spring data jpa and spring mvc And i noticed that my object contact is updated in database automatically.

Here's My Code :

@Transactional
@Controller
public class ContactController {
    @RequestMapping(value="/update_contact ") 
    public @ResponseBody
    String update_contact (...) {
        ...
        Contact contact = contactrespository.findOne(idcontact);

        contact.setName(...);
        ...

    }
}

And without executing contactrespository.save(idcontact); My contact has been changed when i checked the database !
Can you explain me Why ?

Hayi · Accepted Answer · 2014-07-12 14:36:10Z

3

There are many states of an Object :

Persistent: a persistent instance has a representation in the database and an identifier value and it is associated with a Hibernate Session.
Detached : a detached instance is an object that has been persistent, but its Session has been closed.
transient: an object is transient if it has just been instantiated using the new operator, and it is not associated with a Hibernate Session.

In this context The changes are committed to contact because it is a persistent object that has been modified within a transaction because your controller is annotated with @Transactional so it's associated with a Hibernate Session.

It is not a good practice to annotate a Controller with Transactional annotation, it is better used on the service Layer where we invoke the repository not in the controller layer

    @Controller
    public class MyController{

        @Autowired
        private MyService service;

        @RequestMapping ....
        public Contact findContact(String name, ....){
        Contact contact =  service.get(...);
         // other logic 
         }
     }




    @Service
    public class MyService{

        @Autowired
        private MyRepository repository;

        @Transactional(propagation=Propagation.SUPPORTS)
        public Contact get(long id){
         // better throw a notFuondException in here 
        return repository.findOne(id);
        }
    //same for other method like create and update with @Transactional REQUIRED NEW  or      REQUIRED propagation
   }

edited Jul 12, 2014 at 14:36

Hayi

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answered Jul 12, 2014 at 0:24

Rafik BELDI

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15 Comments

Hayi Over a year ago

yes i know they say it's better to put Transactional on service layer but it's not a obligation. So even i'll make a service layer like you said i will have the same behavior -> the object will get updated automatically.

Rafik BELDI Over a year ago

i said it is not a good practice,you risk dirty reads and a mass overflow connections to database, means every time a client loads the page a change is made to the database !! its MVC, it supposed to be light weighted and independent from the persistence layer,it suppose to be a Client to the persistence layer which means to the services.

Hayi Over a year ago

thanks for the information So do you mean even if i don't make something like contactrespository.findOne(idcontact) in my Controller the connection will be opened to the database ?

Hayi Over a year ago

But your answer didn't explain my issue ... your answer is just a advise because even if I put a service layer my issue will still remain.

Rafik BELDI Over a year ago

findOne will return a Persistent instance of Contact , means every change made to this instance will be applied to the database.no change will be maid if the instance is Detached

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