On Fri, Sep 30, 2011 at 5:37 PM, Johannes Dollinger
<emulb...@googlemail.com> wrote:
> The aim of this proposal is to reuse Q objects for models that are related
> through FK or M2M fields.
> A simplified example would be a Q object like
>
> >>> is_blue = Q(blue=True)
> >>> Thing.objects.filter(is_blue)
>
> that should be reused to filter the owners of things:
>
> >>> User.objects.filter(things__blue=True).
>
> Currently, the only way to reuse the Q object would be subquery:
>
> >>> User.objects.filter(things__in=Thing.objects.filter(is_blue)).
>
> I therefore propose the following API:
>
> >>> Q(lookup=value).push('relfield')
I don't like this.
> which would be equivalent to
>
> >>> Q(relfield__lookup=value)
>
> and
>
> >>> qs.filter(relfield=Q(lookup=value))
I do like this
> which would be equivalent to
>
> >>> qs.filter(Q(lookup=value).push('relfield')).
Again, not this.
Are you only proposal the push method as an implementation detail? If
so, don't let it be part of the API proposal itself.
> We then could write
>
> >>> User.objects.filter(things=is_blue)
>
> which is shorter and produces more natural SQL than the subquery solution.
>
> Thoughs? Suggestions?
>
> __
> Johannes
>
>
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