Question

I have these models:

class Model1(models.Model):
    ...

class Model2(models.Model):
    m1 = models.OneToOneField(Model1, related_name='m2')
    ...

I want to get queryset of Model1 objects that have a Model2 defined. Something like this:

objs = Model1.objects.filter('m2'!=None)

but that doesn’t work.

Answer 1

Consider:

objs = Model1.objects.filter('m2'!=None)

The argument in the brackets will be evaluated. What you’re asking of the ORM is, therefore:

objs = Model1.objects.filter(False)

What you meant was:

objs = Model1.objects.filter(m2__isnull=False)

• Link: isnull in the Django QuerySet API Documentation