Thanks Tim for the code optimization ideas. Very pythonic of you ;)
On Sat, Jun 14, 2008 at 10:55 AM, Tim Chase <[EMAIL PROTECTED]>
wrote:
>
> >> cards = Card.objects.all()
> >> if request.POST.get('brand') :
> >> cards = cards.filter(brand = request.POST.get('brand'))
> >> if request.POST.get('year') :
> >> cards = cards.filter(year = request.POST.get('year'))
> >
> > Scott: Very cool, didn't know that was possible. I'm sure this
> > does not hurt
>
> This can even be dumped in a loop, using dictionary kwargs which
> makes it more DRY:
>
> cards = Card.objects.all()
> for field in ('brand', 'year', 'color', 'size'):
> if field in request.POST:
> cards = cards.filter(**{
> field: request.POST.get(field)
> })
>
> This separates out the common code, and reduces the field-names
> to just being entries in a list for which the same action is
> performed for each.
>
> Given that they're ANDed together, you might even be able to just
> build the dictionary, and then unpack that as your filter:
>
> fieldnames = ('brand', 'year', 'color', 'size')
> kwargs = dict(
> (field, request.POST.get(field))
> for field in fieldnames
> if field in request.POST
> )
> cards = Card.objects.filter(**kwargs)
>
> This *could* be reduced to a single (much more opaque) statement,
> but I usually prefer to keep a little readability compared to
>
> cards = Card.objects.filter(**dict(
> (field, request.POST.get(field))
> for field in ('brand', 'year', 'color', 'size')
> if field in request.POST
> ))
>
> I haven't delved into the new QS-RF code to see whether the
> resulting queries differ vastly in meaning/efficiency, but I
> remember there being a subtle difference between chained filters
> vs. multiple filters applied at the same time (though that may
> have only applied to related models).
>
> -tim
>
>
>
>
> >
>
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