How to make an object detached without session closing?

mickey2006 · **Posted:** Wed Sep 06, 2006 9:22 am

Is there an another way to detach an object from the session then just closing this session?

Ananasi · **Posted:** Wed Sep 06, 2006 10:51 am

evict()

mmasters · **Posted:** Wed Sep 06, 2006 11:00 am

The above picture is from the "Hibernate in Action" book. It shows how an object can change from one state to another. I shows that a persistent object can move to a detached state by using evict(), close(), or clear().

mickey2006 · **Posted:** Wed Sep 06, 2006 11:11 am

Thaks guys,

Nevertheless note that evict method should be used if we are sure that all child objects are marked as "evict" as well. Otherwise we'll get some of them still attached to the session.

mmasters · **Posted:** Wed Sep 06, 2006 11:26 am

Don't forget to rate.

mickey2006 · **Posted:** Thu Sep 07, 2006 7:46 am

Have tried the evict method, it didn't help.
Even after Session.clear() I get the exception "Illegal attempt to associate a collection with two open sessions".

I'm trying to copy an object from one database into identical one. I can get an object from session A, iterate it for fully initialization (it is a lazy object) but can't detach it from session A to replicate it into session B. I get the mentioned exception.

Any ideas?

mmasters · **Posted:** Thu Sep 07, 2006 9:50 am

Is the first session closed when you introduce the object to the second session? If that's the case, then you may want to see if 2nd level cache is turned on. If the 2nd level cache is on, then you may want to turn it off.

christian · **Posted:** Thu Sep 07, 2006 9:59 am

The second level cache is transparent and has nothing to do with the stuff you guys are discussing here.

mickey2006 · **Posted:** Thu Sep 07, 2006 10:08 am

So, as far as I understood the Session.evict(obj) and Session.close() stuff won't deatach an object from this session, will it? Do these methods just clear the cash but not deatch objects themselves?

There are many object which are to be iterated and replicated into sessionB, this way I can't close/open session A everytime. Is that really I can't detache objects from session not closing it??

chndu6ue · **Posted:** Thu Sep 07, 2006 12:16 pm

Hi,
Let says u have object b (either came thru query or newly created).
Do following steps to detach the b

Code:

Hibernate.initialize(b);

Code:

sessionA.evict(b);

...
Now b is detached from the sessionA.

Code:

newSession.update(b);

//attach to new session
- Chandra Singh Meena

mmasters · **Posted:** Thu Sep 07, 2006 12:59 pm

mickey2006 wrote:

So, as far as I understood the Session.evict(obj) and Session.close() stuff won't deatach an object from this session, will it? Do these methods just clear the cash but not deatch objects themselves?

There are many object which are to be iterated and replicated into sessionB, this way I can't close/open session A everytime. Is that really I can't detache objects from session not closing it??

Closing the session will detach the object from the session. If changes are made to the object out of the session then they will not be persisted to the database. This is different than if the object was inside of the session. If changes to the object are made inside of a session, then those changes will be persisted to the database when the session is closed/flushed.

For more information:
http://www.hibernate.org/hib_docs/v3/re ... e-overview

mmasters · **Posted:** Thu Sep 07, 2006 1:01 pm

christian wrote:

The second level cache is transparent and has nothing to do with the stuff you guys are discussing here.

Thanks for clearing this up. I wasn't sure if the 2nd level cache would play a role here.