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
29291	Negated Q expressions across a nullable relationship are not properly handled by When expressions.	Bo Marchman		"I've run into an issue with conditional expressions using negated Q objects.

I would expect `qs1` and `qs2` to be equivalent in the following code:

{{{#!python

class Application(models.Model):
    pass

class Score(models.Model):
    application = models.ForeignKey(Application, on_delete=models.PROTECT)
    reviewed = models.BooleanField()

a1 = Application.objects.create()
Score.objects.create(reviewed=False, application=a1)
Score.objects.create(reviewed=True, application=a1)

a2 = Application.objects.create()

qs1 = Application.objects.annotate(
    needs_review=Case(
        When(~Q(score__reviewed=True), then=V(True)),
        default=V(False),
        output_field=BooleanField()
    )
).filter(needs_review=True)

qs2 = Application.objects.filter(
    ~Q(score__reviewed=True)
)

print(qs1) # <QuerySet [<Application: Application object (1)>, <Application: Application object (2)>]>
print(qs2) # <QuerySet [<Application: Application object (2)>]>

assert set(qs1) == set(qs2) 
}}}

The identical `~Q` expression is behaving differently in the context of `Case/When` and `filter`. Am I completely missing something and this is expected behavior?

This is using Django 2.0.4.
"	Bug	new	Database layer (models, ORM)	dev	Normal				Accepted	0	0	0	0	0	0