Fixed #19261 -- Delayed Queryset evaluation in paginators (1b307d6c) · Commits · Dom Sekotill / django

django/core/paginator.py

+5 −0

Original line number	Diff line number	Diff line
		import collections
		from math import ceil

		from django.utils import six


		class InvalidPage(Exception):
		pass

		@@ -89,6 +92,8 @@ class Page(collections.Sequence):
		return len(self.object_list)

		def __getitem__(self, index):
		if not isinstance(index, (slice,) + six.integer_types):
		raise TypeError
		# The object_list is converted to a list so that if it was a QuerySet
		# it won't be a database hit per __getitem__.
		return list(self.object_list)[index]

+22 −0

Original line number	Diff line number	Diff line
		@@ -266,3 +266,25 @@ class ModelPaginationTests(TestCase):
		self.assertEqual(1, p.previous_page_number())
		self.assertEqual(6, p.start_index())
		self.assertEqual(9, p.end_index())

		def test_page_getitem(self):
		"""
		Tests proper behaviour of a paginator page __getitem__ (queryset
		evaluation, slicing, exception raised).
		"""
		paginator = Paginator(Article.objects.all(), 5)
		p = paginator.page(1)

		# Make sure object_list queryset is not evaluated by an invalid __getitem__ call.
		# (this happens from the template engine when using eg: {% page_obj.has_previous %})
		self.assertIsNone(p.object_list._result_cache)
		self.assertRaises(TypeError, lambda: p['has_previous'])
		self.assertIsNone(p.object_list._result_cache)

		# Make sure slicing the Page object with numbers and slice objects work.
		self.assertEqual(p[0], Article.objects.get(headline='Article 1'))
		self.assertQuerysetEqual(p[slice(2)], [
		"<Article: Article 1>",
		"<Article: Article 2>",
		]
		)