Re: [Modeling-users] Couple of questions...

[John L. <jo...@vi...>]

Sender: John Lenton <jo...@ma...>

On Tue, Apr 20, 2004 at 09:46:39AM -0700, Aaron Freeman wrote:
> (1) Is there a debug flag somewhere that dump all SQL queries to the
> console?
>=20
> (2) How are nested joins accomplished?
>=20
> For example, in the AuthorBooks schema, lets assume there is another table
> called publisher that has a 1-M relationship with books, like so (sorry
> about the formatting):
>=20
> .........................................................................=
...
> .............
> .+-----------+.(0,1)..............(0,*).+-------+.(0,*)..............(0,1=
).+
> .|..Writer...|<-author----------books->>|.Book..|<<-books-------publisher=
->|
> .Publisher.|.
> .|-----------|.(nullify)......(cascade).|-------|........................=
..|
> .|.lastName..|..........................|.title.|........................=
..|
> .bizName...|.
> .|.firstName.|..........................|.price.|........................=
..|
> .location..|.
> .|.age.......|.(0,1)....................+-------+........................=
..+
> .|.birthday..|<-pygmalion--+.............................................=
...
> .............
> .+-----------+.(nullify)...|.............................................=
...
> .............
> =20
> .....|....................|..............................................=
...
> ............
> ......+--------------------+.............................................=
...
> .............
> .........................................................................=
...
> .............
>=20
> How would I get writers by publisher?
>
> More specifically, is there an elegant way to do a nested join in a single
> query, or do I just have to do a single writer-book join and then iterate
> over the resultset for the second join?

I don't think so. I'd do it with

   [ i.valueForKeyPath('books.author') for i in ec.fetch('Publisher') ]

which is clean enough for me. I guess what you'd want is for
valueForKeyPath to be callable on a class... :)

--=20
John Lenton (jo...@vi...) -- Random fortune:
Sobre toda cosa guardada guarda tu coraz=F3n, porque de =E9l emana la vida.
		-- Salom=F3n.=20