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
32200	Aggregating when grouping on an ExpressionWrapper omits the expression from the group by	Gordon Wrigley	Hasan Ramezani	"I ran into this with Postgres on Django 3.1.3, I'm not sure what other versions it exists on.

{{{
#!python
print(
    Fred.objects.annotate(
        bob_id__is_null=ExpressionWrapper(
            Q(bob_id=None), 
            output_field=BooleanField()
        )
    ).values(
        ""bob_id__is_null""
    ).annotate(
        id__count=Count(""id"", distinct=True)
    ).values(
        ""bob_id__is_null"", 
        ""id__count""
    ).query
)
}}}

{{{
#!sql
SELECT 
    ""main_fred"".""bob_id"" IS NULL AS ""bob_id__is_null"", 
    COUNT(DISTINCT ""main_fred"".""id"") AS ""id__count"" 
FROM ""main_fred""
GROUP BY ""main_fred"".""bob_id""
}}}

On the last line there the group by has dropped the ""IS NULL"""	Bug	closed	Database layer (models, ORM)	3.1	Release blocker	fixed		gordon.wrigley@… Simon Charette Thodoris Sotiropoulos	Ready for checkin	1	0	0	0	0	0