Hello!

I'm considering using Hibernate, so i'd like to know whether it supports using data from the same table in different persistent classes without creating it twice in memory.
For example:
I've got to database tables, PERSON and ADDRESS, which are related by ADDRESSID. So i create two persistence classes:

class Person
{
Address a;
...
}

class Address
{
...
}

and map them properly.
But also i need (for representation) class like Person-with-address, which contains fields from both tables.
As far as i learnt from documentation, i can map it using <join> tag. But then this new class won't have relations to classes Person and Address, therefore some data frome these DB tables would be created in memory at least twice.
Is there any way I can create class 'Person-with-address', having it persisted in database but with links to Preson and Address, like

class Person_with_address
{
Address a;
Person p;
...
}
,so if 'a' and 'p' have been fetched from DB, Person_with_address will not execute any queries? I need all three classes. Maybe <dynamic-component> can help me here, but I don't see how.
I hope you understand what i meant.

If Hibernate already has the object loaded, you're not going to get an additional query happening - it's very smart.

However, I'd start to call into question your object model if you're going to having a lot of PersonWithAddress.Address equaling PersonWithAddress.Person.Address. This make sense if home/shipping/billing are different addresses, though.

In a larger view, from one Hibernate newbie to another, you might enjoy this piece of insight I gleaned.

My first thoughts in using Hibernate when I started many months ago was that I'd do all my database design and then try to mush Hibernate over it. Doing it that way was awful.

Seriously, don't think about the database. Think about the object model.



Then generate your schema. What you'll find is that Hibernate does not just the right thing, but the efficient thing, often coming up with a better, tighter DDL solution that you'd do by hand.

Each entity, in the case above, has its own life-cycle, and is managed by foreign keys. A couple of annotations later and you can have cascading deletes.

Bottom line: yes, Hibernate will do what you want. In fact, it will be almost magical with its database optimizations.

-wls

Thanks for your answer, i think this is just what i want

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Thanks!