From orm-devel@mailman.tux4web.de  Mon Jun 23 16:20:46 2003
From: orm-devel@mailman.tux4web.de (Kevin Howe)
Date: Mon, 23 Jun 2003 11:20:46 -0400
Subject: [orm-devel] Re: [orm-users] orm with mxODBC
References: <004701c334e1$9a752400$11483141@KHOWE><16111.26376.914604.293044@lisa.tux4web.de><000301c335c2$cc787600$11483141@KHOWE><16112.48487.192188.967115@lisa.tux4web.de><001501c335e0$64d430c0$11483141@KHOWE><16113.60874.919019.973248@lisa.tux4web.de><000401c3368b$2966c1a0$11483141@KHOWE> <16114.50249.881252.116030@lisa.tux4web.de>
Message-ID: <001601c3399b$061e77c0$1a00000a@KHOWE>

> I'm not sure, how to do this, yet. Perhaps there are not going to be
> JOINs, but rather better support for VIEWs (which in turn may contain
> JOINs)...

I read about this on the mailing list, views are an interesting idea.
However if I could put my vote in, the feature I'd like to see implemented
would be this one:

http://mailman.tux4web.de/pipermail/orm-users/2003-May/000015.html

So that you could do queries like the following, which to me seem very
natural:

# fetch only canadian addresses
addresses = person.addresses(country='CA')

A very useful yet simple extension of this would be to allow the passing of
an "operator" object in order to specify a condition:

import ops

# employees older than 25
company.employees(age=ops.GT(25))

# employees of certain ages only
company.employees(age=ops.IN(25, 30)

Where "ops" would contain a class for each operator type. In the above
example we have the "greater than" and "in" operator classes. Each operator
class's __repr__ method would return the appropriate sql condition:

GT would produce: Age > 25
IN would produce: Age IN (25, 30)

Anything more complex than this would be left to runSelect().

- Kevin




From orm-devel@mailman.tux4web.de  Mon Jun 23 20:21:10 2003
From: orm-devel@mailman.tux4web.de (Diedrich Vorberg)
Date: Mon, 23 Jun 2003 21:21:10 +0200
Subject: [orm-devel] Re: [orm-users] subsets of results / operators (was: orm with mxODBC)
In-Reply-To: <001601c3399b$061e77c0$1a00000a@KHOWE>
References: <004701c334e1$9a752400$11483141@KHOWE>
 <16111.26376.914604.293044@lisa.tux4web.de>
 <000301c335c2$cc787600$11483141@KHOWE>
 <16112.48487.192188.967115@lisa.tux4web.de>
 <001501c335e0$64d430c0$11483141@KHOWE>
 <16113.60874.919019.973248@lisa.tux4web.de>
 <000401c3368b$2966c1a0$11483141@KHOWE>
 <16114.50249.881252.116030@lisa.tux4web.de>
 <001601c3399b$061e77c0$1a00000a@KHOWE>
Message-ID: <16119.21286.239189.15227@lisa.tux4web.de>

>So that you could do queries like the following, which to me seem very
>natural:
>
># fetch only canadian addresses
>addresses = person.addresses(country='CA')
Yes, I'll do something like this.

My question: In your idea, are the addresses retrieved from the
database stored in the person object? Right now they are, but I'm not
actually using this 'feature'. It would make ORM reasonably simpler if
that would not be required.

But it also means that:

  for address in person.addresses():
     print address.city


  for address in person.addresses():
     print address.zipcode

will cause two queries. Is that allright? I can think of a chaching
system, too, but this would raise the level of complexity of orm and
the level of subtleness of its use.

>A very useful yet simple extension of this would be to allow the passing of
>an "operator" object in order to specify a condition:
Yes, I like this... I'll think about it. Would you be interested in
writing it yourself...?

Diedrich

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