ExtractMonth from OuterRef in Subquery don't work

[Chiorufarewerin]

Just example code:

DTModel.objects.create(name='1', start_datetime=datetime(2000, 1, 1))
DTModel.objects.create(name='2', start_datetime=datetime(2001, 2, 5))
DTModel.objects.create(name='3', start_datetime=datetime(2002, 1, 7))
DTModel.objects.create(name='4', start_datetime=datetime(2003, 2, 8))

subquery_qs = DTModel.objects.filter(
    name__in=['3', '4'],
    start_datetime__month=ExtractMonth(OuterRef('start_datetime')),
)

qs = DTModel.objects.filter(name__in=['1', '2'])
qs = qs.annotate(related_name=Subquery(subquery_qs.values('name')[:1]))

This code raises where ExtractMonth(OuterRef('start_datetime')):

'ResolvedOuterRef' object has no attribute 'output_field'

It can be works with something like:

start_datetime__month=ExtractMonth(Func(OuterRef('start_datetime'), function='', output_field=DateTimeField())),

Or if redefine class:

class ExtractMonthCustom(ExtractMonth):
    def resolve_expression(self, *args, **kwargs):
        return super(Extract, self).resolve_expression(*args, **kwargs)

[Simon Charette]

It can be works with something like:

start_datetime__month=ExtractMonth(Func(OuterRef('start_datetime'), function='', output_field=DateTimeField())),

You can also use ExpressionWrapper for ​this purpose in the mean time.

start_datetime__month=ExtractMonth(ExpressionWrapper(OuterRef('start_datetime'), output_field=DateTimeField()))

[Mariusz Felisiak]

​PR

[Mariusz Felisiak <felisiak.mariusz@…>]

In 3954bf50:

Fixed #32750 -- Fixed crash of Extract() transform on OuterRef() expressions.

Thanks Simon Charette for the review.