Re: Data map classes

From: Andrei Adamchik (aadamchi..obox.com)
Date: Fri Mar 30 2001 - 11:49:50 EST


At 11:44 AM 3/30/2001 -0500, Michael Misha Shengaout wrote:

>Andrei Adamchik wrote:
>
> >
> > A) ObjEntity-DbEntity relationship:
> >
> > Why do we need to have objectEntity pointer in DbEntity? (DbAttribute -
> > ObjAttribute has the same problem). I guess it makes sense to use layered
> > design, where bottom layer (Db* classes) is not aware of the layers built
> > on top (Obj* classes), while top layer can access everything underneath it.
> > Do you see any reason to access ObjEntity, etc. from DbEntity ? I don't.
> >
>
>We will need to navigate from the database table to the object entities when
>processing the result sets, so there will be a need for the "backwards"
>navigation

I agree to everything except of the above. Processing result sets always
happens in some context... The context should know the original query, and
query will know Object entities involved. If context is ignorant of
ObjEntities, then well... we can not create real objects, maybe some
generic ones...

You see, this will help to separate DB part from Object part in a clean
way. I am not sure what are other potential uses of DbEntities (transparent
join tables, for example), but if there are some, they will need not be
dependent on ObjEntity definition and existance.

Andrei



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