El vie, 21-07-2006 a las 10:21 -0400, Pete Taylor escribió:
> Lorenzo,
> I've run into a very (very!) similar situation, and ended up writing
> some wrapper/simplification utilities for zc.relationship.
> zc.relationship is wonderfully powerful, but a bit complex.  It's use
> is intuitive once you wade through the 2000+ lines of documentation
> (which is worthwhile reading), but it's a bit intimidating at first.

Ok, I was afraid of an answer like this because in a recent thread I've
read Jim Fulton saying that we are trying to use zodb as a relational
database which is a shame and I think I agree with that quote.

So that's why I tried not to use external packages like zc.relationship
and stick to a plain object model with intrinsic relations modeled as
simple object attributes. The obvious question is: does this allow
powerful queries like the ones I mentioned in my first email or I should
switch and use extrinsic relations for this kind of features?

> I've packaged up my wrapper utilities as a product, and ZPL2.1'd the
> code.  If you'd like it, even just for reference, let me know.  I
> intend to release it more publicly shortly.

Sure! I'm 120% interested in reading your solution since reinventing the
wheel is something I always try to avoid. Thanks a lot for you kindly


>   It implements nice
> adapters, so objects implementing a particular marker interface can do
> things like:
> client = MyClient()
> q = IQuestion(obj)
> orders = q.ask_as_subject("owns")
> orders
> ['<some.Order object at...>']
> you can also build filter functions that take the relationship you're
> targeting as an argument, and check any property of the relationship
> in question...
> let me know if you'd like a copy.  if not, then i'd suggest going
> through at least the containers.txt in zc.relationship.
> as far as the catalog goes, i'd get into using hurry.query as fast as
> possible ;)
> On 7/21/06, Lorenzo Gil Sanchez <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > I've been following recent discussion about relations in Zope. Both
> > intrinsic and extrinsic relationships.
> >
> > For the following question lets assume we have a IClient and an IOrder
> > content types and the IOrder schema has a IClient attribute called 'client'.
> >
> > Reading previous messages to this list I understand that's the best way
> > to model this kind of intrinsic relationship between an Order and a Client.
> >
> > Now the question: using a Catalog, what should I do to answer these kind
> > of questions:
> >
> >   - Give me all orders whose client's name starts with 'John'
> >
> >   - Give me all orders whose client's age is between 20 and 30
> >
> >   - Give me all orders for a certain client
> >
> > I guess I need to use a special kind of FieldIndex for objects but I'm
> > new to the Catalog land and I'm pretty much lost.
> >
> > Any help, examples or pointers to detailed doc are greatly appreciated :-)
> >
> > Best regards,
> >
> > Lorenzo Gil
> > _______________________________________________
> > Zope3-users mailing list
> > Zope3-users@zope.org
> > http://mail.zope.org/mailman/listinfo/zope3-users
> >

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