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

Use isnull.

users_without_reports = User.objects.filter(report__isnull=True)
users_with_reports = User.objects.filter(report__isnull=False).distinct()

When you use isnull=False, the distinct() is required to prevent duplicate results.