id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
31397	Support qs.filter(related=Q(...)).	Roman Odaisky	nobody	"It would be very helpful to be able to use Q objects with related models, especially if some other code generates the Q objects. Use case:

{{{
def bestsellers(q):
    qs = Author.objects.filter(q).annotate(total_sold=Sum(""book__n_sold""))
    ...
}}}
Suppose that later the calculations become so complex that they can’t be expressed in terms of aggregate functions, thus Python code has to be written instead, and the queryset changes models:
{{{
def bestsellers(q):  # q still contains fields from the Author model
    qs = Book.objects.filter(???)
    for book in qs:
        ...
}}}
It would be natural to try to write `Book.objects.filter(author=q)`, but this syntax isn’t supported.

I suggest that `Q(model=Q(a=b, c=d))` be allowed with the same effect as `Q(model__a=b, model__c=d)` (recursively if the inner Q is nested).

The implementation does not seem to be particularly complex. This function does most of the work:
{{{
def prefix_q(prefix, q):
    """""" Q(prefix=q) === prefix_q(prefix, q) """"""
    if isinstance(q, tuple):
        return (prefix + ""__"" + q[0], q[1])

    return Q(*[prefix_q(prefix, c) for c in q.children],
        _connector=q.connector, _negated=q.negated)
}}}"	New feature	closed	Database layer (models, ORM)	3.0	Normal	duplicate			Unreviewed	0	0	0	0	0	0