From ca61195827efdf6ec54e8280e4cfd9a34f07b8b4 Mon Sep 17 00:00:00 2001
From: Artem Rizhov <artem.rizhov@gmail.com>
Date: Wed, 8 Oct 2014 18:27:17 +0300
Subject: [PATCH] Fixed #23555 -- Avoided suppressing IndexError in
QuerySet.first() and .last()
---
django/db/models/query.py | 18 ++++++++----------
tests/get_earliest_or_latest/models.py | 15 +++++++++++++++
tests/get_earliest_or_latest/tests.py | 26 +++++++++++++++++++++++++-
3 files changed, 48 insertions(+), 11 deletions(-)
diff --git a/django/db/models/query.py b/django/db/models/query.py
index be5892a371..9371aa14e0 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -516,21 +516,19 @@ 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:
- return None
+ 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:
- return None
+ 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):
"""
diff --git a/tests/get_earliest_or_latest/models.py b/tests/get_earliest_or_latest/models.py
index cd62cf0104..55096f5a2c 100644
--- a/tests/get_earliest_or_latest/models.py
+++ b/tests/get_earliest_or_latest/models.py
@@ -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()
diff --git a/tests/get_earliest_or_latest/tests.py b/tests/get_earliest_or_latest/tests.py
index 742c70bc41..de3307b1a6 100644
--- a/tests/get_earliest_or_latest/tests.py
+++ b/tests/get_earliest_or_latest/tests.py
@@ -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()