In a Django QuerySet, how to filter for “not exists” in a many-to-one relationship

Question

I have two models like this:

class User(models.Model):
    email = models.EmailField()

class Report(models.Model):
    user = models.ForeignKey(User)


        

Answer 1

To filter users who do not have reports associated with them try this:

users = User.objects.exclude(id__in=[elem.user.id for elem in Report.objects.all()])