#13489: Arbitrary Q filter on related model fields
---------------------------+------------------------------------------------
Reporter: jnothman | Owner: nobody
Status: new | Milestone:
Component: Uncategorized | Version: 1.1
Keywords: | Stage: Unreviewed
Has_patch: 0 |
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Given a model with a foreign key, e.g. the classic Entry / Blog example,
we may want to select/aggregate over entries contained in blogs with
certain features. We can e.g. perform a filter over the joined relation:
{{{
Entry.objects.filter(blog__tagline__contains="foobar")
}}}
As far as I know, we cannot define a Q instance defined to filter Blog
(which may be pre-defined for other purposes) to perform the same filter
over a join:
The closest we can get (in 1.1) is:
{{{
q = Q(tagline__contains="foobar")
Entry.objects.filter(blog_in=q)
}}}
which performs a sub-select query, with the same results, but different
efficiency, and different fields available for output.
I propose one of two syntax options:
{{{
Entry.objects.filter(blog_has=q)
}}}
or:
{{{
Entry.objects.filter(q.apply_to_field('blog'))
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/13489>
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