Opened 7 years ago

Last modified 6 years ago

#29291 new Bug

Conditional expressions and ~Q queries — at Initial Version

Reported by: Bo Marchman Owned by: nobody
Component: Database layer (models, ORM) Version: dev
Severity: Normal Keywords:
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

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:

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?

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