Fixed #23555 -- Avoided suppressing IndexError in QuerySet.first() and .last() (ca611958) · Commits · Dom Sekotill / django

django/db/models/query.py

+8 −10

Original line number	Diff line number	Diff line
		@@ -516,20 +516,18 @@ class QuerySet(object):
		"""
		Returns the first object of a query, returns None if no match is found.
		"""
		qs = self if self.ordered else self.order_by('pk')
		try:
		return qs[0]
		except IndexError:
		objects = list((self if self.ordered else self.order_by('pk'))[:1])
		if objects:
		return objects[0]
		return None

		def last(self):
		"""
		Returns the last object of a query, returns None if no match is found.
		"""
		qs = self.reverse() if self.ordered else self.order_by('-pk')
		try:
		return qs[0]
		except IndexError:
		objects = list((self.reverse() if self.ordered else self.order_by('-pk'))[:1])
		if objects:
		return objects[0]
		return None

		def in_bulk(self, id_list):

+15 −0

Original line number	Diff line number	Diff line
		@@ -14,3 +14,18 @@ class Person(models.Model):
		name = models.CharField(max_length=30)
		birthday = models.DateField()
		# Note that this model doesn't have "get_latest_by" set.


		# Ticket #23555 - model with an intentionally broken QuerySet.__iter__ method.

		class IndexErrorQuerySet(models.QuerySet):
		"""
		Emulates the case when some internal code raises an unexpected
		IndexError.
		"""
		def __iter__(self):
		raise IndexError


		class IndexErrorArticle(Article):
		objects = IndexErrorQuerySet.as_manager()

+25 −1

Original line number	Diff line number	Diff line
		@@ -4,7 +4,7 @@ from datetime import datetime

		from django.test import TestCase

		from .models import Article, Person
		from .models import Article, Person, IndexErrorArticle


		class EarliestOrLatestTests(TestCase):
		@@ -122,6 +122,9 @@ class EarliestOrLatestTests(TestCase):
		self.assertRaises(AssertionError, Person.objects.latest)
		self.assertEqual(Person.objects.latest("birthday"), p2)


		class TestFirstLast(TestCase):

		def test_first(self):
		p1 = Person.objects.create(name="Bob", birthday=datetime(1950, 1, 1))
		p2 = Person.objects.create(name="Alice", birthday=datetime(1961, 2, 3))
		@@ -152,3 +155,24 @@ class EarliestOrLatestTests(TestCase):
		self.assertIs(
		Person.objects.filter(birthday__lte=datetime(1940, 1, 1)).last(),
		None)

		def test_index_error_not_suppressed(self):
		"""
		#23555 -- Unexpected IndexError exceptions in QuerySet iteration
		shouldn't be suppressed.
		"""
		def check():
		# We know that we've broken the __iter__ method, so the queryset
		# should always raise an exception.
		self.assertRaises(IndexError, lambda: IndexErrorArticle.objects.all()[0])
		self.assertRaises(IndexError, IndexErrorArticle.objects.all().first)
		self.assertRaises(IndexError, IndexErrorArticle.objects.all().last)

		check()

		# And it does not matter if there are any records in the DB.
		IndexErrorArticle.objects.create(
		headline="Article 1", pub_date=datetime(2005, 7, 26),
		expire_date=datetime(2005, 9, 1)
		)
		check()