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From Jérémy DE ROYER <jeremy.dero...@ingencys.net>
Subject Re: Migrate Horizontal Inheritance (EOF) to Cayenne
Date Sat, 13 Apr 2019 15:18:31 GMT
Hi Andrus,

We will do the migration during the summer, so it depends how long is « soon » 😀

We built our apps as a burger with a lot of abstract classes on the main(s) framework to be
sure that every (upper) frameworks know about each other classes even if not (really) implemented.

As an example,

We have (abstract) classes called « AbstractCompany » and « AbstractCustomer » on the
main framework

On the middle commercial framework we implement classes « Invoice » and « Quote » that
are linked to « AbstractCompany » and « AbstractCustomer ».

And… on the « e-business » framework we do implement the classe « Customer » (that extends
« AbstractCustomer »)

And… on the « crm » framework we do implement the classe « Company » (that extends «
AbstractCompany »)

So without any effort, the « Invoice » and « Quote » are able to see/select/link « customer
» and « company », just with adding the framework(s) to the (final) customer app.

I don’t know if it’s clear enough but I hope it may help to understand the importance
of horizontal inheritance as we can’t rewirte all our logic.

Jérémy

Le 13 avr. 2019 à 16:45, Andrus Adamchik <andrus@objectstyle.org<mailto:andrus@objectstyle.org>>
a écrit :

Hi Jérémy,

Yes, there's still no horizontal inheritance in Cayenne. It wasn't attractive from performance
standpoint, so nobody really advocated for it to happen so far. Now that I've finally met
a number of people who care about "horizontal", we are thinking of prioritizing it. So it
may happen (relatively) soon.

Is the game over ?

Not really. You can just map all those tables as separate entities. Queries may be a little
more annoying to write (especially if you have relationships *to* the base abstract entity),
but it shouldn't be a show stopper. And outside of persistence operations the objects can
all implement a single interface, so once you get them out of DB, you'll have the ability
to treat them as children of a single ancestor.

Andrus



On Apr 13, 2019, at 4:26 PM, Jérémy DE ROYER <jeremy.deroyer@ingencys.net<mailto:jeremy.deroyer@ingencys.net>>
wrote:

Hello,

I’m trying to migrate (eo)models using horizontal inheritance (over multiple frameworks)
but without any success : it’s not possible to generate the Java classes using Cayenne Modeler.

I did a test with only one entity (and table) : that works great (and easy).

I’ve created a second entity (and  table) : that works great and easy.

I’ve set up an horizontal inheritance between the two entities (and table) : Cayenne forces
me to use the same table for both entities

In the 3.0's doc, I’ve read : “As of this writing Cayenne does not support horizontal
inheritance. It may in the future”.

Is it still true in the 4.0 ? 4.1 ? Is the game over ? (as I can not use vertical inheritance)
🤕

Thank’s,

Jérémy


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