How to get primary key of newly inserted object

gdiscc · **Joined:** Thu May 10, 2007 10:46 pm **Posts:** 4

In Hibernate EntityManager, I use "entityManager.persist(obj)" to insert a newly created obj to database. If the primary key is auto generated by database, is there any way to retrieve the key?

adamgibbons · **Joined:** Sat Apr 21, 2007 11:01 pm **Posts:** 144

You should be able to just save/persist the object and then call getId()...

gdiscc · **Joined:** Thu May 10, 2007 10:46 pm **Posts:** 4

the "save" method can not be found in EntityManager class, should other class be used here?

adamgibbons · **Joined:** Sat Apr 21, 2007 11:01 pm **Posts:** 144

Use some DAOs, personaly I have mine extend Spring's HibernateDaoSupport and then my save method would look like:

Code:

    public void save(CostPeriod transientInstance) {
        if (log.isDebugEnabled()) {
          log.debug("saving CostPeriod instance");
        }
       
        getHibernateTemplate().saveOrUpdate(transientInstance);
        if (log.isDebugEnabled()) {        
           log.debug("save successful");
        }
    }

oldkeybo · **Joined:** Tue May 23, 2006 3:41 am **Posts:** 6

Adam,
could you explain more detail, with example desirable, how it works.
I mean my DAO implementation based on Entity manager and as I understand correctly, if I will use your DAO support - I should refuse Entity manager or I somethink missed

hlfsousa · **Posted:** Fri May 11, 2007 12:11 pm

Dude, relax. You should be just fine with your EntityManager. It has different naming but the same meaning. Once you invoke entityManager.persist(someInstance), you should be able to get someInstance's id by calling someInstance.getId() -- assuming your ID property is named id. If for some reason this does not work, flush() the entity manager before calling getId(). Just take it easy ;)

Henrique

gdiscc · **Joined:** Thu May 10, 2007 10:46 pm **Posts:** 4

hlfsousa wrote:

Dude, relax. You should be just fine with your EntityManager. It has different naming but the same meaning. Once you invoke entityManager.persist(someInstance), you should be able to get someInstance's id by calling someInstance.getId() -- assuming your ID property is named id. If for some reason this does not work, flush() the entity manager before calling getId(). Just take it easy ;)

Henrique

Here is my code:

Code:

entityManager.persist(transientInstance);
entityManager.flush();
log.debug("persist successful:" + transientInstance.getId());

The generated id in DB is 10, transientInstance.getId() gives 0. Did I mistake anything here?

oldkeybo · **Joined:** Tue May 23, 2006 3:41 am **Posts:** 6

Ye, Henrique was write- we should relax :O)
Just forget transientInstance.

Code:

        Epistle epi = new Epistle();
        epi.setEpiContent(proba);
        epi.setEpiFooter(probaFooter);
        epi.setEpiHeader(probaHeader);
        em.persist(epi);
       log.debug("persist successful:" + epi.getId());

Here Epistle - is table from DB, em- EntityManager

gdiscc · **Joined:** Thu May 10, 2007 10:46 pm **Posts:** 4

I found the problem - I didn't specify ID generation type in Object class definition.

Code:

@Id
   @Column(name = "id", unique = true, nullable = false)
   public int getId() {
      return this.id;
   }

It worked after putting ID generation Type:

Code:

   @Id [b]@GeneratedValue(strategy=GenerationType.AUTO)[/b]
   @Column(name = "id", unique = true, nullable = false)
   public int getId() {
      return this.id;
   }

Thanks for all the help!