>>> try:
>>> restaurant = p2.restaurant
>>> except Restaurant.DoesNotExist:
>>> print "Place has no restaurant!"
>>> else:
>>> # Do something with p2's restaurant here.
User.objects.annotate(
no_reports=~Exists(Reports.objects.filter(user__eq=OuterRef('pk')))
).filter(
email__startswith='a',
no_reports=True
)