Derek
Would you distinguish between what is achievable in a specific ORM
such as Hibernate from JPA in this statement or would you think it
applies to all. I've got to go with hibernate in any case because of
widespread use of UserTypes. Unlike Greg, in my case I can hand-craft
all my hibernate
Well, in my real-world experience I've never had very complex models and
I've never used TABLE-PER-CLASS either, so I don't really have a feel for
what's not possible. Generally I think that JPA (which is a subset of
Hibernate) covers a good portion of people's needs for ORM, but it
definitely has
Derek,
i completely concur. i wanted to give it a serious go, however, before i
abandoned it. The issue is that so much of the incumbent technology goes
across this object-relational boundary, i needed a simple case to justify
walking away from this technology. This example provides it. To see
Oops, forgot a member of the hierarchy, inline below:
On Tue, Jun 23, 2009 at 3:19 PM, Kris
Nuttycombekris.nuttyco...@gmail.com wrote:
I'm just so puzzled by this thread because I have the following entity
hierarchy in my app:
@Entity
@Inheritance(strategy = InheritanceType.JOINED)
I'm just so puzzled by this thread because I have the following entity
hierarchy in my app:
@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@Table(name = payment_source_transaction)
public abstract class PaymentSourceTransactionT extends PaymentSourceT
extends
Kris,
Thanks for this code sample. i will study and see if it offers a way around
the conundrum. In the meantime, here's a code
samplehttp://svn.biosimilarity.com/src/open/codesamples/trunk/hibernate/hbex/illustrating
exactly what i'm talking about.
Best wishes,
--greg
On Tue, Jun 23, 2009 at
I don't understand from the code sample why AbstractContainer has to be an
entity or
have a table or id annotation. I'd be looking at just using the
@MappedSuperclass annotation.
On Wed, Jun 24, 2009 at 9:27 AM, Meredith Gregory
lgreg.mered...@gmail.comwrote:
Kris,
Thanks for this code
Kris,
Do you have a self-contained, compilable sample i could compare to the one i
made? i can craft one from your snippet below, but it'd be a better
comparison if you had one already.
Best wishes,
--greg
On Tue, Jun 23, 2009 at 2:21 PM, Kris Nuttycombe
kris.nuttyco...@gmail.comwrote:
Oliver,
Thanks. This proposal has been put forward before.
- The code is generated. If the top class is annotated @MappedSuperclass,
why not label every abstract class that is top of its hierarchy
@MappedSuperclass. That's the simplest change to the compilation strategy
that
Actually, I don't think I would be looking at @MappedSuperclass either.
Whats your database schema? Is it always a Legacy database or are you
creating it new?
Are the java entities you are trying to create, read only?
Why aren't you using Scala's JPA?
If you are creating a complex parent-child
Kris,
Thanks for the suggestion. i've now got a tiny little example that compiles
on its own that illustrates the problem. Changing the inheritance strategy
to JOINED makes no difference. Hibernate still does the wrong thing.
Best wishes,
--greg
On Mon, Jun 22, 2009 at 8:55 AM, Kris Nuttycombe
Kris,
Here http://svn.biosimilarity.com/src/open/codesamples/trunk/hibernate/ is
a link to the self-contained example that now uses just Java. i included the
target dir in the repo to speed up investigation, but you can just blow that
away and build from scratch. The example is currently written
Something I just want to throw out into the discussion: Since you're using
table-per-class, having a @Table annotation on AbstractContainer doesn't do
anything since abstract classes can't have instances. Tables are only
generated for abstract classes if you're using a JOINED inheritance
strategy.
Derek,
You are correct and i noted and reported this on Scala on Friday. However,
if you have a chain of the form
AbstractClass - Class -contains- AbstractClass -Class -contains- ...
The @MappedSuperclass solution fails at level 2.
Best wishes,
--greg
On Mon, Jun 22, 2009 at 3:52 PM, Derek
P.S. While i am waiting for the Hibernate folks to respond to the issue, i
am looking into Stefan Zeiger's LINQ implementation for Scala more
seriously. If it is reasonably stable, this is a much better target for my
compilation scheme, anyway.
On Mon, Jun 22, 2009 at 3:55 PM, Meredith Gregory
Ah, sorry, I lost track of the thread.
On Mon, Jun 22, 2009 at 4:55 PM, Meredith Gregory
lgreg.mered...@gmail.comwrote:
Derek,
You are correct and i noted and reported this on Scala on Friday. However,
if you have a chain of the form
AbstractClass - Class -contains- AbstractClass -Class
For sufficiently complex relationships, JPA is not a good fit. Beyond a
certain point it's usually simpler to roll your own. I think that this is
somewhat of a failing of the model, but it's not a simple problem to solve
in the generic case.
Derek
On Mon, Jun 22, 2009 at 6:45 PM, Derek
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