Fixed #21563 -- Single related object descriptors should work with `hasattr`. (75924cfa) · Commits · Dom Sekotill / django

django/db/models/fields/related.py

+30 −5

Original line number	Diff line number	Diff line
		@@ -156,6 +156,16 @@ class SingleRelatedObjectDescriptor(six.with_metaclass(RenameRelatedObjectDescri
		self.related = related
		self.cache_name = related.get_cache_name()

		@cached_property
		def RelatedObjectDoesNotExist(self):
		# The exception isn't created at initialization time for the sake of
		# consistency with `ReverseSingleRelatedObjectDescriptor`.
		return type(
		str('RelatedObjectDoesNotExist'),
		(self.related.model.DoesNotExist, AttributeError),
		{}
		)

		def is_cached(self, instance):
		return hasattr(instance, self.cache_name)

		@@ -200,9 +210,12 @@ class SingleRelatedObjectDescriptor(six.with_metaclass(RenameRelatedObjectDescri
		setattr(rel_obj, self.related.field.get_cache_name(), instance)
		setattr(instance, self.cache_name, rel_obj)
		if rel_obj is None:
		raise self.related.model.DoesNotExist("%s has no %s." % (
		raise self.RelatedObjectDoesNotExist(
		"%s has no %s." % (
		instance.__class__.__name__,
		self.related.get_accessor_name()))
		self.related.get_accessor_name()
		)
		)
		else:
		return rel_obj

		@@ -255,6 +268,17 @@ class ReverseSingleRelatedObjectDescriptor(six.with_metaclass(RenameRelatedObjec
		self.field = field_with_rel
		self.cache_name = self.field.get_cache_name()

		@cached_property
		def RelatedObjectDoesNotExist(self):
		# The exception can't be created at initialization time since the
		# related model might not be resolved yet; `rel.to` might still be
		# a string model reference.
		return type(
		str('RelatedObjectDoesNotExist'),
		(self.field.rel.to.DoesNotExist, AttributeError),
		{}
		)

		def is_cached(self, instance):
		return hasattr(instance, self.cache_name)

		@@ -321,8 +345,9 @@ class ReverseSingleRelatedObjectDescriptor(six.with_metaclass(RenameRelatedObjec
		setattr(rel_obj, self.field.related.get_cache_name(), instance)
		setattr(instance, self.cache_name, rel_obj)
		if rel_obj is None and not self.field.null:
		raise self.field.rel.to.DoesNotExist(
		"%s has no %s." % (self.field.model.__name__, self.field.name))
		raise self.RelatedObjectDoesNotExist(
		"%s has no %s." % (self.field.model.__name__, self.field.name)
		)
		else:
		return rel_obj

tests/one_to_one/tests.py

+4 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,10 @@ class OneToOneTests(TestCase):
		# p2 doesn't have an associated restaurant.
		with self.assertRaisesMessage(Restaurant.DoesNotExist, 'Place has no restaurant'):
		self.p2.restaurant
		# The exception raised on attribute access when a related object
		# doesn't exist should be an instance of a subclass of `AttributeError`
		# refs #21563
		self.assertFalse(hasattr(self.p2, 'restaurant'))

		def test_setter(self):
		# Set the place using assignment notation. Because place is the primary

tests/reverse_single_related/tests.py

+11 −2

Original line number	Diff line number	Diff line
		@@ -33,5 +33,14 @@ class ReverseSingleRelatedTests(TestCase):
		# of the "bare" queryset. Usually you'd define this as a property on the class,
		# but this approximates that in a way that's easier in tests.
		Source.objects.use_for_related_fields = True
		try:
		private_item = Item.objects.get(pk=private_item.pk)
		self.assertRaises(Source.DoesNotExist, lambda: private_item.source)
		finally:
		Source.objects.use_for_related_fields = False

		def test_hasattr_single_related(self):
		# The exception raised on attribute access when a related object
		# doesn't exist should be an instance of a subclass of `AttributeError`
		# refs #21563
		self.assertFalse(hasattr(Item(), 'source'))