Modularization of my application.

keeskuip · **Joined:** Sat Sep 20, 2003 1:09 pm **Posts:** 8

Hello,

I am about to split my application into a 'base' with (optional) 'modules'.
The base and modules will persist classes using hibernate.

Most of these classes in the modules are specific to that module.
But sometimes the module will have to extend a persistent class
of the 'base'.
For instance :
I have a base-class "Article".
The module "Lot-tracking" will extend this Article with the
property "LotNumber" (and several others).

So "Article" will get an extra property when the module "Lot-tracking"
is activated.

So I'm looking for a way to 'expand' to a hmb.xml-file.
I now I can do it with ant and an xslt-transformation, but I would
like to see it as a standard feature in hibernate.
Maybe mark the expansion with an attribute.
maybe something like :

The Article in the 'base' :

Code:

<hibernate-mapping>
  <class name="Article" table="Article">
     <property name="Code"/>
     <property name="Name"/>
  </class>
</hibernate-mapping>

Expanding the Article in module 'Lot-tracking' :

Code:

<hibernate-mapping>
  <class name="Article" table="Article" expand="true">
     <property name="LotNumber"/>
  </class>
</hibernate-mapping>

Any thoughts on this ?

Kees Kuip.

steve · **Posted:** Sat Sep 20, 2003 2:41 pm

Have you looked at the subclass mapping element?

max · **Posted:** Sat Sep 20, 2003 3:38 pm

subclass and joined-subclass now supports an extends attribute and can be used to extend existing mapped classes.

This is a new feature in Hibernate 2.1 and is currently only availbale in the v21branch

keeskuip · **Joined:** Sat Sep 20, 2003 1:09 pm **Posts:** 8

steve wrote:

Have you looked at the subclass mapping element?

Yes, I looked at it, but I do not want to subclass "Article".
There will be more than one module which will need to 'expand' the "Article".
So subclass which has single-inheritance is no solution.

Kees.

max · **Posted:** Sun Sep 21, 2003 7:27 am

keeskuip wrote:

steve wrote:

Have you looked at the subclass mapping element?

Yes, I looked at it, but I do not want to subclass "Article".
There will be more than one module which will need to 'expand' the "Article".
So subclass which has single-inheritance is no solution.

Kees.

That's evil! ;)

You should just allow for your modules to overrule the Article definitions then! How do you handle extending your own compiled classes ?

keeskuip · **Joined:** Sat Sep 20, 2003 1:09 pm **Posts:** 8

Quote:

That's evil! ;)

Why is that evil ?

Subclassing for no apparent reason is evil !
You can read every design-book on that.

Quote:

How do you handle extending your own compiled classes ?

I generate my compiled classes (with velocity), so there is no problem.

Kees.

max · **Posted:** Sun Sep 21, 2003 10:18 am

keeskuip wrote:

Quote:

That's evil! ;)

Why is that evil ?

Subclassing for no apparent reason is evil !
You can read every design-book on that.

Quote:

How do you handle extending your own compiled classes ?

I generate my compiled classes (with velocity), so there is no problem.

Kees.

Ok - so it's not like you want one part of your system having Article and some other part of the system Article + the extras.

You just want Article + extras allover ?

Then why not generate your hbm.xmls with velocity or combine them with xml external entities or something ?

keeskuip · **Joined:** Sat Sep 20, 2003 1:09 pm **Posts:** 8

Yes, thats what I'm doing right now.

But I thought it would be nice if was in standard Hibernate.

Thanks,
Kees.