Mapping: Generator. Increment&assigned at the same time

arelendil · **Posted:** Mon Sep 11, 2006 6:21 am

Hi, there!
Here is my problem:
I need to use 2 classes of generator at the same time: increment and assigned.
What for:
In usual work in adding items to the table increment generator is used. It's normal.

But I need to move old data to new database. I must feel the table with old IDs.
method setId() doesn't work if I use increment generator. If I use assigned generator I must use setId() always.

Can I use two at the same time, or i must find another solvation?

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

You can either map the class twice and distinguish between the two mappings via the entity-name attribute of the class element, or write your own generator class (see refdocs section 5.1.4.1 and elsewhere) which does something fancy like:

Code:

public class SometimesIncrementGenerator extends org.hibernate.id.IncrementGenerator
{
  @Override
  public synchronized Serializable
  generate(SessionImplementor session, Object object)
  {
    final Serializable id =
      session.getEntityPersister(entityName, obj)
             .getIdentifier(obj, session.getEntityMode());
    if (id == nulll || id == -1)
    {
      return super.generate(session, object);
    }

    return id;
  }
}

I don't know if autoboxing can handle Serializable, you may have to do something else to get the value from the id variable, probably involving instanceof and casting. That's left as an exercise for the reader :)

arelendil · **Posted:** Tue Sep 12, 2006 4:26 am

I made my generator class.
Now I need to use it in mapping class.
How?
<generator class="SometimesIncrement"/> doesn't work

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

You need to mention the package.