Asure not too many queries are run

tests/videodinges/factories.py

@@ -51,10 +51,18 @@ def _create_with_defaults(model: Type[T], kwargs: dict, **defaults) -> T:
 		:param defaults: default keyword arguments to use when not mentioned in kwargs
 	"""
 
+	_next_pk = 0
+	def next_pk():
+		# Queries next pk only one time during creation
+		nonlocal _next_pk
+		if _next_pk == 0:
+			_next_pk = _query_next_pk(model)
+		return _next_pk
+
 	for k, v in defaults.items():
 		if callable(v) and not k in kwargs:
 			if len(signature(v).parameters) == 1:
-				result = v(_next_pk(model))
+				result = v(next_pk())
 			else:
 				result = v()
 			defaults[k] = result
@@ -62,7 +70,7 @@ def _create_with_defaults(model: Type[T], kwargs: dict, **defaults) -> T:
 	return model.objects.create(**{**defaults, **kwargs})
 
 
-def _next_pk(model: Type[T]) -> int:
+def _query_next_pk(model: Type[T]) -> int:
 	try:
 		return model.objects.order_by('-pk').first().pk + 1
 	except AttributeError:

tests/videodinges/test_factories/test_video.py

@@ -34,3 +34,8 @@ class VideoTestCase(TestCase):
 		self.assertEqual(video3.description, 'Description 3')
 		self.assertIsInstance(video3.created_at, datetime)
 		self.assertIsInstance(video3.updated_at, datetime)
+
+	def test_factory_runs_only_2_queries(self):
+		""" Factory should only use 2 queries: one for selecting primary key, and one for inserting record """
+		with self.assertNumQueries(2):
+			video = factories.create(Video)