I found this reply to an earlier posting quite usefull.
http://www.mail-archive.com/orion-interest@orionserver.com/msg12085.html
On 16 Apr 2001 17:23:15 -0700, Rian Schmidt wrote:
> Oh boy... OK, maybe that was a bad example. "Read more about entity beans"
> is not very useful advice in any case. I just didn't want to explain our
> business model to ask the question.
>
> Try the situation where the top level is Vehicle -> Manufacturer -> Model or
> something many-to-many on each layer. My point is that I want to be able to
> "skip a layer" in the finder. Is that possible? If you don't know, or the
> answer is no, please just say that or ignore my question and move on. If
> you have an actual answer or alternative approach that might work, I'd be
> very appreciative to hear it.
>
> For what it's worth, I want to do it this way, as opposed to using some kind
> of bean-based (logical model) test or pseudo-BMP thing because, due to the
> volume of "3rd level (in my example)" entities running a findAll on them is
> performance-limiting and I'd rather not stick SQL directly in my beans.
>
> Thanks,
> Rian
> --
> Rian Schmidt
> [EMAIL PROTECTED]
>
> ----- Original Message -----
> From: "elephantwalker" <[EMAIL PROTECTED]>
> To: "Orion-Interest" <[EMAIL PROTECTED]>
> Sent: Monday, April 16, 2001 2:54 PM
> Subject: RE: findBy referencing another entity reference
>
>
> > Rian,
> >
> > This is much too sql centric. You should resolve your entity beans around
> > business methods. So I would start off by reading more about entity beans.
> > Theserverside.com, for example has a download on an excellent book for
> > entity beans. As for the sql, you are talking a one to one relationship
> for
> > the car/model and a one to many relationship for the manufacturer/model.
> > There should be some examples of this on the sun's j2ee site. I know that
> > they specifically discuss this issue.
> >
> > Regards,
> >
> > the elephantwalker
> >
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of Rian Schmidt
> > Sent: Monday, April 16, 2001 2:23 PM
> > To: Orion-Interest
> > Subject: findBy referencing another entity reference
> >
> >
> > Hi all,
> >
> > How about this scenario:
> > There are three entities: manufacturer, model, car (as an example)
> > model knows directly which manufacturer it is, car knows which model it
> is,
> > but car has to do a model.getManufacturer to find out its manufacturer...
> >
> > OK, so what I wanna know is can I a findByManufacturer for car? I'd
> > like to be able to do something like this:
> > query="$model.manufacturer = $1"
> >
> > Now, I know that I could specify a sub-query with the actual persistence
> > name of the other entity's thang, something like:
> > query="$model in (select $model from model where manufacturer_id = $1)"
> > but it strikes me that Orion won't know what I'm going on about, and best
> > case, will have to talk to the database each time. Either way, I had to
> put
> > the persistence name into the orion-ejb-jar.xml file, which is not
> goodness.
> >
> > Is it possible maybe to say something like:
> > query="model in ($1)"
> > where $1 is a Collection of models taken from
> ModelHome.findByManufacturer?
> >
> > Any thoughts on the best way to approach this?
> >
> > Thanks,
> > Rian
> > --
> > Rian Schmidt
> > [EMAIL PROTECTED]
> >
> >
> >
>
>
>
--
Adam Cassar
Technical Development Manager
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