Re: [Hibernate] generated field as part of composite key

[Gavin K. <ga...@ap...>]

> Would implementing ClassPersister be the way to go for this? At first
> (and uninformed) glance it would seems like all I'd need to do is
> override insert() from EntityPersister and instead of setting the ID to
> the IDENTITY value returned, set a particular field in the ID to the
> IDENTITY value returned.

Well, almost. Might be a little bit of extra fiddling because there are two
versions of insert:

(1) take an id and return nothing
(2) take just the fields and return an id (meant for use with IDENTITY
columns)

You *have* to use version (2) because that version is called immediately
from save() rather than buffered for later.

To make sure (2) gets called you need to:

* override getIdentifierGenerator() to return an instance of NativeGenerator
(because its always Assigned for composite id classes)
* override isIdentifierAssignedByInsert() to return true
* Override insert() as you described. Return the id from this method.

Oh, a couple more things:

* EntityPersister is currently declared final and I will probably leave it
that way so use delegation, not inheritence
* I need to wire in a little bit of code to allow the mapping document to
specify a ClassPersister implementation class (I'll do that tomorrow)
* I changed the ClassPersister interface earlier today to generalize it a
bit. Grab a CVS update.

Gavin

>
> > Hold on.....somethings not right.....the IDENTITY column has to be
unique of
> > its own accord, right?
>
> Yes, but for various reasons the IDENTITY field is not the only field in
> the key. The joys of retrofitting :-)

So MS SQL can generate