Persist an object with detached objects

Christian Gesswagner · **Joined:** Wed Jun 07, 2006 6:11 am **Posts:** 20

Hi!

How can i persist an transient object with detached objects?

That means, I've got an transient address object which should be filled with the detached objects City and Zipcode.

With the method merge it works, but I do not get the ID of the address object, but it is written to the database (with the method persist I'll get an ID). The method refresh fails, because the address object does not have an ID. Why? How can I persist this address object correctly, thus I get an ID.

Thanks!
Christian

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

You must use persist, save or saveOrUpdate. Don't worry about the nested objects being detached: detached objects still have the correct IDs, and that's all you need to save the references correctly.

If you want to re-attach the detached nested objects, call refresh on the address object after persisting it.

Christian Gesswagner · **Joined:** Wed Jun 07, 2006 6:11 am **Posts:** 20

Hibernate version: 3.2.0.cr2
Hibernate Annotations: 3.2.0.CR1
Hibernate Entity Manager: 3.2.0.CR1
JBoss version: 4.0.4.GA
EJB3 version: EJB-3.0 RC8-FD
Name and version of the database you are using: Ingres 3.0.105

The problem is, that I can not use detached objects in the persist method, because this will cause a org.hibernate.PersistentObjectException: detached entity passed to persist. And I can only call the methods persist and merge, because I'm using an EntityManager.

Here is my code example:

Code:

City city = new City();
city.setName("cityName");
Zipcode code = new Zipcode();
code.setCode("myCode");

em.persist(city);
em.persist(code);

Now I want to create a new Address (zipcode and city must not be null in the database!).

Code:

Address ad = new Address();
ad.setCity(city); // detached object city
ad.setZipcode(code); // detached object code

Code:

em.persist(ad);

// this will cause the exception and adds no data to the database

or

Code:

em.merge(ad);

// this will work (adds data to the database), but the address object will not get an ID (getId() == null)!

HB_Dude · **Joined:** Mon Sep 26, 2005 11:10 am **Posts:** 5

I am moving from straight Hibernate to the HibernateEntityManager.

I have a City, State, and ZipCode which were saved in another session, then I create a new Address with the City, State, and ZipCode. (In my case, the City, State, and ZipCode do have proper id fields). When I go to save the address using em.persist() I get:

org.hibernate.PersistentObjectException: detached entity passed to ...

I did this all the time with stright hibernate. My hbm.xml files have cascade=all on the relationships to the dependant objects.

I am using the same versions mentioned above, except I'm not inside JBoss at this point, just trying to get the JUnits working.

Any suggestions would be greatly appreciated.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

You can't have done that. Session.persist() accepts only transient objects, not detached ones. The exception is correct, your code is wrong.

It is polite to start a new topic to ask a new question.