Doubt about detached entity passed to persist

[Frederico Benevides]

I load my object A, when I try to persist even I changed the Id of the object I got this exception. When I change to merge I don't get. So even my object is detached from the container, the container still has reference to this object?

How long the container will have this reference?

[Shivani Chandna]

Hello Frederico,

I have not understood your question correctly, Could you please re-frame it?

When a detached entity is passed for persistence the entity becomes managed until the end of transaction (If the persistence context has the type defined as transaction).

For merge - the copy of the object is created and then a managed entity is returned. If the managed entity exists before then it is updated or else a new one is created and returned to the client.

Regards,
Shivani

[Frederico Benevides]

Hello, thank for your answer.

I'll explain with examples.

When I'm on the client and use remote session beans to find my "Person entity":

ManagerPerson mp = (ManagerPerson) ctx.lookup("ManagerPersonBean/remote");
 
Person person = mp.find(1)
 
person.setId(2);
mp.save(person) // don't work. detached entity (using persist)
 
mp.update(person) // work, using merge.
 
// but if I do this.
Person person = new Person("Frederico")
 
mp.save(person) // ok......
    

So I would like to understand how the container knows the the object Person that I find one "day" was managed or attached to him. I changed the Id just to test if it would let me to attach just to think as "new object". But not. I can't.

Since I'm using remote, and my method calls finished, why the container knows that object need to attached again, and don't let me add as a new object. So I think the container has a reference to this object that I find even I finished the method's call.

[Shivani Chandna]

Hello Frederico,

I created a Stateless session bean named ManagePerson with methods save,find, update.And Person entity class with fields id and name.
In save method of I called entityMgrObject.persist(personObj);

//client code // mpr is intfc to ManagePerson
Person p = mpr.find(1); //1 is a record existing already.
p.setId(22);
mpr.save(p); // This creates another person record in database with id=22

So, for me a new record does get created on persist.
Now ,could you please share your complete code so that I can see where the problem is?

Regards,
Shivani