django/tests/lookup/tests.py

from __future__ import unicode_literals

import collections
from datetime import datetime
from operator import attrgetter
from unittest import skipUnless

from django.core.exceptions import FieldError
from django.db import connection
from django.test import (
    TestCase, TransactionTestCase, ignore_warnings, skipUnlessDBFeature,
)
from django.utils.deprecation import RemovedInDjango20Warning

from .models import Article, Author, Game, MyISAMArticle, Player, Season, Tag


class LookupTests(TestCase):

    def setUp(self):
        # Create a few Authors.
        self.au1 = Author.objects.create(name='Author 1')
        self.au2 = Author.objects.create(name='Author 2')
        # Create a couple of Articles.
        self.a1 = Article.objects.create(headline='Article 1', pub_date=datetime(2005, 7, 26), author=self.au1)
        self.a2 = Article.objects.create(headline='Article 2', pub_date=datetime(2005, 7, 27), author=self.au1)
        self.a3 = Article.objects.create(headline='Article 3', pub_date=datetime(2005, 7, 27), author=self.au1)
        self.a4 = Article.objects.create(headline='Article 4', pub_date=datetime(2005, 7, 28), author=self.au1)
        self.a5 = Article.objects.create(headline='Article 5', pub_date=datetime(2005, 8, 1, 9, 0), author=self.au2)
        self.a6 = Article.objects.create(headline='Article 6', pub_date=datetime(2005, 8, 1, 8, 0), author=self.au2)
        self.a7 = Article.objects.create(headline='Article 7', pub_date=datetime(2005, 7, 27), author=self.au2)
        # Create a few Tags.
        self.t1 = Tag.objects.create(name='Tag 1')
        self.t1.articles.add(self.a1, self.a2, self.a3)
        self.t2 = Tag.objects.create(name='Tag 2')
        self.t2.articles.add(self.a3, self.a4, self.a5)
        self.t3 = Tag.objects.create(name='Tag 3')
        self.t3.articles.add(self.a5, self.a6, self.a7)

    def test_exists(self):
        # We can use .exists() to check that there are some
        self.assertTrue(Article.objects.exists())
        for a in Article.objects.all():
            a.delete()
        # There should be none now!
        self.assertFalse(Article.objects.exists())

    def test_lookup_int_as_str(self):
        # Integer value can be queried using string
        self.assertQuerysetEqual(Article.objects.filter(id__iexact=str(self.a1.id)),
                                 ['<Article: Article 1>'])

    @skipUnlessDBFeature('supports_date_lookup_using_string')
    def test_lookup_date_as_str(self):
        # A date lookup can be performed using a string search
        self.assertQuerysetEqual(
            Article.objects.filter(pub_date__startswith='2005'),
            [
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )

    def test_iterator(self):
        # Each QuerySet gets iterator(), which is a generator that "lazily"
        # returns results using database-level iteration.
        self.assertIsInstance(Article.objects.iterator(), collections.Iterator)

        self.assertQuerysetEqual(
            Article.objects.iterator(),
            [
                'Article 5',
                'Article 6',
                'Article 4',
                'Article 2',
                'Article 3',
                'Article 7',
                'Article 1',
            ],
            transform=attrgetter('headline')
        )
        # iterator() can be used on any QuerySet.
        self.assertQuerysetEqual(
            Article.objects.filter(headline__endswith='4').iterator(),
            ['Article 4'],
            transform=attrgetter('headline'))

    def test_count(self):
        # count() returns the number of objects matching search criteria.
        self.assertEqual(Article.objects.count(), 7)
        self.assertEqual(Article.objects.filter(pub_date__exact=datetime(2005, 7, 27)).count(), 3)
        self.assertEqual(Article.objects.filter(headline__startswith='Blah blah').count(), 0)

        # count() should respect sliced query sets.
        articles = Article.objects.all()
        self.assertEqual(articles.count(), 7)
        self.assertEqual(articles[:4].count(), 4)
        self.assertEqual(articles[1:100].count(), 6)
        self.assertEqual(articles[10:100].count(), 0)

        # Date and date/time lookups can also be done with strings.
        self.assertEqual(Article.objects.filter(pub_date__exact='2005-07-27 00:00:00').count(), 3)

    def test_in_bulk(self):
        # in_bulk() takes a list of IDs and returns a dictionary mapping IDs to objects.
        arts = Article.objects.in_bulk([self.a1.id, self.a2.id])
        self.assertEqual(arts[self.a1.id], self.a1)
        self.assertEqual(arts[self.a2.id], self.a2)
        self.assertEqual(
            Article.objects.in_bulk(),
            {
                self.a1.id: self.a1,
                self.a2.id: self.a2,
                self.a3.id: self.a3,
                self.a4.id: self.a4,
                self.a5.id: self.a5,
                self.a6.id: self.a6,
                self.a7.id: self.a7,
            }
        )
        self.assertEqual(Article.objects.in_bulk([self.a3.id]), {self.a3.id: self.a3})
        self.assertEqual(Article.objects.in_bulk({self.a3.id}), {self.a3.id: self.a3})
        self.assertEqual(Article.objects.in_bulk(frozenset([self.a3.id])), {self.a3.id: self.a3})
        self.assertEqual(Article.objects.in_bulk((self.a3.id,)), {self.a3.id: self.a3})
        self.assertEqual(Article.objects.in_bulk([1000]), {})
        self.assertEqual(Article.objects.in_bulk([]), {})
        self.assertEqual(Article.objects.in_bulk(iter([self.a1.id])), {self.a1.id: self.a1})
        self.assertEqual(Article.objects.in_bulk(iter([])), {})
        with self.assertRaises(TypeError):
            Article.objects.in_bulk(headline__startswith='Blah')

    def test_values(self):
        # values() returns a list of dictionaries instead of object instances --
        # and you can specify which fields you want to retrieve.
        self.assertSequenceEqual(
            Article.objects.values('headline'),
            [
                {'headline': 'Article 5'},
                {'headline': 'Article 6'},
                {'headline': 'Article 4'},
                {'headline': 'Article 2'},
                {'headline': 'Article 3'},
                {'headline': 'Article 7'},
                {'headline': 'Article 1'},
            ],
        )
        self.assertSequenceEqual(
            Article.objects.filter(pub_date__exact=datetime(2005, 7, 27)).values('id'),
            [{'id': self.a2.id}, {'id': self.a3.id}, {'id': self.a7.id}],
        )
        self.assertSequenceEqual(
            Article.objects.values('id', 'headline'),
            [
                {'id': self.a5.id, 'headline': 'Article 5'},
                {'id': self.a6.id, 'headline': 'Article 6'},
                {'id': self.a4.id, 'headline': 'Article 4'},
                {'id': self.a2.id, 'headline': 'Article 2'},
                {'id': self.a3.id, 'headline': 'Article 3'},
                {'id': self.a7.id, 'headline': 'Article 7'},
                {'id': self.a1.id, 'headline': 'Article 1'},
            ],
        )
        # You can use values() with iterator() for memory savings,
        # because iterator() uses database-level iteration.
        self.assertSequenceEqual(
            list(Article.objects.values('id', 'headline').iterator()),
            [
                {'headline': 'Article 5', 'id': self.a5.id},
                {'headline': 'Article 6', 'id': self.a6.id},
                {'headline': 'Article 4', 'id': self.a4.id},
                {'headline': 'Article 2', 'id': self.a2.id},
                {'headline': 'Article 3', 'id': self.a3.id},
                {'headline': 'Article 7', 'id': self.a7.id},
                {'headline': 'Article 1', 'id': self.a1.id},
            ],
        )
        # The values() method works with "extra" fields specified in extra(select).
        self.assertSequenceEqual(
            Article.objects.extra(select={'id_plus_one': 'id + 1'}).values('id', 'id_plus_one'),
            [
                {'id': self.a5.id, 'id_plus_one': self.a5.id + 1},
                {'id': self.a6.id, 'id_plus_one': self.a6.id + 1},
                {'id': self.a4.id, 'id_plus_one': self.a4.id + 1},
                {'id': self.a2.id, 'id_plus_one': self.a2.id + 1},
                {'id': self.a3.id, 'id_plus_one': self.a3.id + 1},
                {'id': self.a7.id, 'id_plus_one': self.a7.id + 1},
                {'id': self.a1.id, 'id_plus_one': self.a1.id + 1},
            ],
        )
        data = {
            'id_plus_one': 'id+1',
            'id_plus_two': 'id+2',
            'id_plus_three': 'id+3',
            'id_plus_four': 'id+4',
            'id_plus_five': 'id+5',
            'id_plus_six': 'id+6',
            'id_plus_seven': 'id+7',
            'id_plus_eight': 'id+8',
        }
        self.assertSequenceEqual(
            Article.objects.filter(id=self.a1.id).extra(select=data).values(*data.keys()),
            [{
                'id_plus_one': self.a1.id + 1,
                'id_plus_two': self.a1.id + 2,
                'id_plus_three': self.a1.id + 3,
                'id_plus_four': self.a1.id + 4,
                'id_plus_five': self.a1.id + 5,
                'id_plus_six': self.a1.id + 6,
                'id_plus_seven': self.a1.id + 7,
                'id_plus_eight': self.a1.id + 8,
            }],
        )
        # You can specify fields from forward and reverse relations, just like filter().
        self.assertSequenceEqual(
            Article.objects.values('headline', 'author__name'),
            [
                {'headline': self.a5.headline, 'author__name': self.au2.name},
                {'headline': self.a6.headline, 'author__name': self.au2.name},
                {'headline': self.a4.headline, 'author__name': self.au1.name},
                {'headline': self.a2.headline, 'author__name': self.au1.name},
                {'headline': self.a3.headline, 'author__name': self.au1.name},
                {'headline': self.a7.headline, 'author__name': self.au2.name},
                {'headline': self.a1.headline, 'author__name': self.au1.name},
            ],
        )
        self.assertSequenceEqual(
            Author.objects.values('name', 'article__headline').order_by('name', 'article__headline'),
            [
                {'name': self.au1.name, 'article__headline': self.a1.headline},
                {'name': self.au1.name, 'article__headline': self.a2.headline},
                {'name': self.au1.name, 'article__headline': self.a3.headline},
                {'name': self.au1.name, 'article__headline': self.a4.headline},
                {'name': self.au2.name, 'article__headline': self.a5.headline},
                {'name': self.au2.name, 'article__headline': self.a6.headline},
                {'name': self.au2.name, 'article__headline': self.a7.headline},
            ],
        )
        self.assertSequenceEqual(
            (
                Author.objects
                .values('name', 'article__headline', 'article__tag__name')
                .order_by('name', 'article__headline', 'article__tag__name')
            ),
            [
                {'name': self.au1.name, 'article__headline': self.a1.headline, 'article__tag__name': self.t1.name},
                {'name': self.au1.name, 'article__headline': self.a2.headline, 'article__tag__name': self.t1.name},
                {'name': self.au1.name, 'article__headline': self.a3.headline, 'article__tag__name': self.t1.name},
                {'name': self.au1.name, 'article__headline': self.a3.headline, 'article__tag__name': self.t2.name},
                {'name': self.au1.name, 'article__headline': self.a4.headline, 'article__tag__name': self.t2.name},
                {'name': self.au2.name, 'article__headline': self.a5.headline, 'article__tag__name': self.t2.name},
                {'name': self.au2.name, 'article__headline': self.a5.headline, 'article__tag__name': self.t3.name},
                {'name': self.au2.name, 'article__headline': self.a6.headline, 'article__tag__name': self.t3.name},
                {'name': self.au2.name, 'article__headline': self.a7.headline, 'article__tag__name': self.t3.name},
            ],
        )
        # However, an exception FieldDoesNotExist will be thrown if you specify
        # a non-existent field name in values() (a field that is neither in the
        # model nor in extra(select)).
        with self.assertRaises(FieldError):
            Article.objects.extra(select={'id_plus_one': 'id + 1'}).values('id', 'id_plus_two')
        # If you don't specify field names to values(), all are returned.
        self.assertSequenceEqual(
            Article.objects.filter(id=self.a5.id).values(),
            [{
                'id': self.a5.id,
                'author_id': self.au2.id,
                'headline': 'Article 5',
                'pub_date': datetime(2005, 8, 1, 9, 0)
            }],
        )

    def test_values_list(self):
        # values_list() is similar to values(), except that the results are
        # returned as a list of tuples, rather than a list of dictionaries.
        # Within each tuple, the order of the elements is the same as the order
        # of fields in the values_list() call.
        self.assertSequenceEqual(
            Article.objects.values_list('headline'),
            [
                ('Article 5',),
                ('Article 6',),
                ('Article 4',),
                ('Article 2',),
                ('Article 3',),
                ('Article 7',),
                ('Article 1',),
            ],
        )
        self.assertSequenceEqual(
            Article.objects.values_list('id').order_by('id'),
            [(self.a1.id,), (self.a2.id,), (self.a3.id,), (self.a4.id,), (self.a5.id,), (self.a6.id,), (self.a7.id,)],
        )
        self.assertSequenceEqual(
            Article.objects.values_list('id', flat=True).order_by('id'),
            [self.a1.id, self.a2.id, self.a3.id, self.a4.id, self.a5.id, self.a6.id, self.a7.id],
        )
        self.assertSequenceEqual(
            Article.objects.extra(select={'id_plus_one': 'id+1'}).order_by('id').values_list('id'),
            [(self.a1.id,), (self.a2.id,), (self.a3.id,), (self.a4.id,), (self.a5.id,), (self.a6.id,), (self.a7.id,)],
        )
        self.assertSequenceEqual(
            Article.objects.extra(select={'id_plus_one': 'id+1'}).order_by('id').values_list('id_plus_one', 'id'),
            [
                (self.a1.id + 1, self.a1.id),
                (self.a2.id + 1, self.a2.id),
                (self.a3.id + 1, self.a3.id),
                (self.a4.id + 1, self.a4.id),
                (self.a5.id + 1, self.a5.id),
                (self.a6.id + 1, self.a6.id),
                (self.a7.id + 1, self.a7.id)
            ],
        )
        self.assertSequenceEqual(
            Article.objects.extra(select={'id_plus_one': 'id+1'}).order_by('id').values_list('id', 'id_plus_one'),
            [
                (self.a1.id, self.a1.id + 1),
                (self.a2.id, self.a2.id + 1),
                (self.a3.id, self.a3.id + 1),
                (self.a4.id, self.a4.id + 1),
                (self.a5.id, self.a5.id + 1),
                (self.a6.id, self.a6.id + 1),
                (self.a7.id, self.a7.id + 1)
            ],
        )
        args = ('name', 'article__headline', 'article__tag__name')
        self.assertSequenceEqual(
            Author.objects.values_list(*args).order_by(*args),
            [
                (self.au1.name, self.a1.headline, self.t1.name),
                (self.au1.name, self.a2.headline, self.t1.name),
                (self.au1.name, self.a3.headline, self.t1.name),
                (self.au1.name, self.a3.headline, self.t2.name),
                (self.au1.name, self.a4.headline, self.t2.name),
                (self.au2.name, self.a5.headline, self.t2.name),
                (self.au2.name, self.a5.headline, self.t3.name),
                (self.au2.name, self.a6.headline, self.t3.name),
                (self.au2.name, self.a7.headline, self.t3.name),
            ],
        )
        with self.assertRaises(TypeError):
            Article.objects.values_list('id', 'headline', flat=True)

    def test_get_next_previous_by(self):
        # Every DateField and DateTimeField creates get_next_by_FOO() and
        # get_previous_by_FOO() methods. In the case of identical date values,
        # these methods will use the ID as a fallback check. This guarantees
        # that no records are skipped or duplicated.
        self.assertEqual(repr(self.a1.get_next_by_pub_date()), '<Article: Article 2>')
        self.assertEqual(repr(self.a2.get_next_by_pub_date()), '<Article: Article 3>')
        self.assertEqual(repr(self.a2.get_next_by_pub_date(headline__endswith='6')), '<Article: Article 6>')
        self.assertEqual(repr(self.a3.get_next_by_pub_date()), '<Article: Article 7>')
        self.assertEqual(repr(self.a4.get_next_by_pub_date()), '<Article: Article 6>')
        with self.assertRaises(Article.DoesNotExist):
            self.a5.get_next_by_pub_date()
        self.assertEqual(repr(self.a6.get_next_by_pub_date()), '<Article: Article 5>')
        self.assertEqual(repr(self.a7.get_next_by_pub_date()), '<Article: Article 4>')

        self.assertEqual(repr(self.a7.get_previous_by_pub_date()), '<Article: Article 3>')
        self.assertEqual(repr(self.a6.get_previous_by_pub_date()), '<Article: Article 4>')
        self.assertEqual(repr(self.a5.get_previous_by_pub_date()), '<Article: Article 6>')
        self.assertEqual(repr(self.a4.get_previous_by_pub_date()), '<Article: Article 7>')
        self.assertEqual(repr(self.a3.get_previous_by_pub_date()), '<Article: Article 2>')
        self.assertEqual(repr(self.a2.get_previous_by_pub_date()), '<Article: Article 1>')

    def test_escaping(self):
        # Underscores, percent signs and backslashes have special meaning in the
        # underlying SQL code, but Django handles the quoting of them automatically.
        Article.objects.create(headline='Article_ with underscore', pub_date=datetime(2005, 11, 20))

        self.assertQuerysetEqual(
            Article.objects.filter(headline__startswith='Article'),
            [
                '<Article: Article_ with underscore>',
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__startswith='Article_'),
            ['<Article: Article_ with underscore>']
        )
        Article.objects.create(headline='Article% with percent sign', pub_date=datetime(2005, 11, 21))
        self.assertQuerysetEqual(
            Article.objects.filter(headline__startswith='Article'),
            [
                '<Article: Article% with percent sign>',
                '<Article: Article_ with underscore>',
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__startswith='Article%'),
            ['<Article: Article% with percent sign>']
        )
        Article.objects.create(headline='Article with \\ backslash', pub_date=datetime(2005, 11, 22))
        self.assertQuerysetEqual(
            Article.objects.filter(headline__contains='\\'),
            ['<Article: Article with \ backslash>']
        )

    def test_exclude(self):
        Article.objects.create(headline='Article_ with underscore', pub_date=datetime(2005, 11, 20))
        Article.objects.create(headline='Article% with percent sign', pub_date=datetime(2005, 11, 21))
        Article.objects.create(headline='Article with \\ backslash', pub_date=datetime(2005, 11, 22))

        # exclude() is the opposite of filter() when doing lookups:
        self.assertQuerysetEqual(
            Article.objects.filter(headline__contains='Article').exclude(headline__contains='with'),
            [
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.exclude(headline__startswith="Article_"),
            [
                '<Article: Article with \\ backslash>',
                '<Article: Article% with percent sign>',
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.exclude(headline="Article 7"),
            [
                '<Article: Article with \\ backslash>',
                '<Article: Article% with percent sign>',
                '<Article: Article_ with underscore>',
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 1>',
            ]
        )

    def test_none(self):
        # none() returns a QuerySet that behaves like any other QuerySet object
        self.assertQuerysetEqual(Article.objects.none(), [])
        self.assertQuerysetEqual(Article.objects.none().filter(headline__startswith='Article'), [])
        self.assertQuerysetEqual(Article.objects.filter(headline__startswith='Article').none(), [])
        self.assertEqual(Article.objects.none().count(), 0)
        self.assertEqual(Article.objects.none().update(headline="This should not take effect"), 0)
        self.assertQuerysetEqual([article for article in Article.objects.none().iterator()], [])

    def test_in(self):
        # using __in with an empty list should return an empty query set
        self.assertQuerysetEqual(Article.objects.filter(id__in=[]), [])
        self.assertQuerysetEqual(
            Article.objects.exclude(id__in=[]),
            [
                '<Article: Article 5>',
                '<Article: Article 6>',
                '<Article: Article 4>',
                '<Article: Article 2>',
                '<Article: Article 3>',
                '<Article: Article 7>',
                '<Article: Article 1>',
            ]
        )

    def test_in_different_database(self):
        with self.assertRaisesMessage(
            ValueError,
            "Subqueries aren't allowed across different databases. Force the "
            "inner query to be evaluated using `list(inner_query)`."
        ):
            list(Article.objects.filter(id__in=Article.objects.using('other').all()))

    def test_error_messages(self):
        # Programming errors are pointed out with nice error messages
        with self.assertRaisesMessage(
            FieldError,
            "Cannot resolve keyword 'pub_date_year' into field. Choices are: "
            "author, author_id, headline, id, pub_date, tag"
        ):
            Article.objects.filter(pub_date_year='2005').count()

        with self.assertRaisesMessage(
            FieldError,
            "Unsupported lookup 'starts' for CharField or join on the field "
            "not permitted."
        ):
            Article.objects.filter(headline__starts='Article')

    def test_relation_nested_lookup_error(self):
        # An invalid nested lookup on a related field raises a useful error.
        msg = 'Related Field got invalid lookup: editor'
        with self.assertRaisesMessage(FieldError, msg):
            Article.objects.filter(author__editor__name='James')

    def test_regex(self):
        # Create some articles with a bit more interesting headlines for testing field lookups:
        for a in Article.objects.all():
            a.delete()
        now = datetime.now()
        Article.objects.create(pub_date=now, headline='f')
        Article.objects.create(pub_date=now, headline='fo')
        Article.objects.create(pub_date=now, headline='foo')
        Article.objects.create(pub_date=now, headline='fooo')
        Article.objects.create(pub_date=now, headline='hey-Foo')
        Article.objects.create(pub_date=now, headline='bar')
        Article.objects.create(pub_date=now, headline='AbBa')
        Article.objects.create(pub_date=now, headline='baz')
        Article.objects.create(pub_date=now, headline='baxZ')
        # zero-or-more
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'fo*'),
            ['<Article: f>', '<Article: fo>', '<Article: foo>', '<Article: fooo>']
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__iregex=r'fo*'),
            [
                '<Article: f>',
                '<Article: fo>',
                '<Article: foo>',
                '<Article: fooo>',
                '<Article: hey-Foo>',
            ]
        )
        # one-or-more
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'fo+'),
            ['<Article: fo>', '<Article: foo>', '<Article: fooo>']
        )
        # wildcard
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'fooo?'),
            ['<Article: foo>', '<Article: fooo>']
        )
        # leading anchor
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'^b'),
            ['<Article: bar>', '<Article: baxZ>', '<Article: baz>']
        )
        self.assertQuerysetEqual(Article.objects.filter(headline__iregex=r'^a'), ['<Article: AbBa>'])
        # trailing anchor
        self.assertQuerysetEqual(Article.objects.filter(headline__regex=r'z$'), ['<Article: baz>'])
        self.assertQuerysetEqual(
            Article.objects.filter(headline__iregex=r'z$'),
            ['<Article: baxZ>', '<Article: baz>']
        )
        # character sets
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'ba[rz]'),
            ['<Article: bar>', '<Article: baz>']
        )
        self.assertQuerysetEqual(Article.objects.filter(headline__regex=r'ba.[RxZ]'), ['<Article: baxZ>'])
        self.assertQuerysetEqual(
            Article.objects.filter(headline__iregex=r'ba[RxZ]'),
            ['<Article: bar>', '<Article: baxZ>', '<Article: baz>']
        )

        # and more articles:
        Article.objects.create(pub_date=now, headline='foobar')
        Article.objects.create(pub_date=now, headline='foobaz')
        Article.objects.create(pub_date=now, headline='ooF')
        Article.objects.create(pub_date=now, headline='foobarbaz')
        Article.objects.create(pub_date=now, headline='zoocarfaz')
        Article.objects.create(pub_date=now, headline='barfoobaz')
        Article.objects.create(pub_date=now, headline='bazbaRFOO')

        # alternation
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'oo(f|b)'),
            [
                '<Article: barfoobaz>',
                '<Article: foobar>',
                '<Article: foobarbaz>',
                '<Article: foobaz>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__iregex=r'oo(f|b)'),
            [
                '<Article: barfoobaz>',
                '<Article: foobar>',
                '<Article: foobarbaz>',
                '<Article: foobaz>',
                '<Article: ooF>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'^foo(f|b)'),
            ['<Article: foobar>', '<Article: foobarbaz>', '<Article: foobaz>']
        )

        # greedy matching
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'b.*az'),
            [
                '<Article: barfoobaz>',
                '<Article: baz>',
                '<Article: bazbaRFOO>',
                '<Article: foobarbaz>',
                '<Article: foobaz>',
            ]
        )
        self.assertQuerysetEqual(
            Article.objects.filter(headline__iregex=r'b.*ar'),
            [
                '<Article: bar>',
                '<Article: barfoobaz>',
                '<Article: bazbaRFOO>',
                '<Article: foobar>',
                '<Article: foobarbaz>',
            ]
        )

    @skipUnlessDBFeature('supports_regex_backreferencing')
    def test_regex_backreferencing(self):
        # grouping and backreferences
        now = datetime.now()
        Article.objects.create(pub_date=now, headline='foobar')
        Article.objects.create(pub_date=now, headline='foobaz')
        Article.objects.create(pub_date=now, headline='ooF')
        Article.objects.create(pub_date=now, headline='foobarbaz')
        Article.objects.create(pub_date=now, headline='zoocarfaz')
        Article.objects.create(pub_date=now, headline='barfoobaz')
        Article.objects.create(pub_date=now, headline='bazbaRFOO')
        self.assertQuerysetEqual(
            Article.objects.filter(headline__regex=r'b(.).*b\1'),
            ['<Article: barfoobaz>', '<Article: bazbaRFOO>', '<Article: foobarbaz>']
        )

    def test_regex_null(self):
        """
        Ensure that a regex lookup does not fail on null/None values
        """
        Season.objects.create(year=2012, gt=None)
        self.assertQuerysetEqual(Season.objects.filter(gt__regex=r'^$'), [])

    def test_regex_non_string(self):
        """
        Ensure that a regex lookup does not fail on non-string fields
        """
        Season.objects.create(year=2013, gt=444)
        self.assertQuerysetEqual(Season.objects.filter(gt__regex=r'^444$'), ['<Season: 2013>'])

    def test_regex_non_ascii(self):
        """
        Ensure that a regex lookup does not trip on non-ASCII characters.
        """
        Player.objects.create(name='\u2660')
        Player.objects.get(name__regex='\u2660')

    def test_nonfield_lookups(self):
        """
        Ensure that a lookup query containing non-fields raises the proper
        exception.
        """
        with self.assertRaises(FieldError):
            Article.objects.filter(headline__blahblah=99)
        with self.assertRaises(FieldError):
            Article.objects.filter(headline__blahblah__exact=99)
        with self.assertRaises(FieldError):
            Article.objects.filter(blahblah=99)

    def test_lookup_collision(self):
        """
        Ensure that genuine field names don't collide with built-in lookup
        types ('year', 'gt', 'range', 'in' etc.).
        Refs #11670.
        """

        # Here we're using 'gt' as a code number for the year, e.g. 111=>2009.
        season_2009 = Season.objects.create(year=2009, gt=111)
        season_2009.games.create(home="Houston Astros", away="St. Louis Cardinals")
        season_2010 = Season.objects.create(year=2010, gt=222)
        season_2010.games.create(home="Houston Astros", away="Chicago Cubs")
        season_2010.games.create(home="Houston Astros", away="Milwaukee Brewers")
        season_2010.games.create(home="Houston Astros", away="St. Louis Cardinals")
        season_2011 = Season.objects.create(year=2011, gt=333)
        season_2011.games.create(home="Houston Astros", away="St. Louis Cardinals")
        season_2011.games.create(home="Houston Astros", away="Milwaukee Brewers")
        hunter_pence = Player.objects.create(name="Hunter Pence")
        hunter_pence.games.set(Game.objects.filter(season__year__in=[2009, 2010]))
        pudge = Player.objects.create(name="Ivan Rodriquez")
        pudge.games.set(Game.objects.filter(season__year=2009))
        pedro_feliz = Player.objects.create(name="Pedro Feliz")
        pedro_feliz.games.set(Game.objects.filter(season__year__in=[2011]))
        johnson = Player.objects.create(name="Johnson")
        johnson.games.set(Game.objects.filter(season__year__in=[2011]))

        # Games in 2010
        self.assertEqual(Game.objects.filter(season__year=2010).count(), 3)
        self.assertEqual(Game.objects.filter(season__year__exact=2010).count(), 3)
        self.assertEqual(Game.objects.filter(season__gt=222).count(), 3)
        self.assertEqual(Game.objects.filter(season__gt__exact=222).count(), 3)

        # Games in 2011
        self.assertEqual(Game.objects.filter(season__year=2011).count(), 2)
        self.assertEqual(Game.objects.filter(season__year__exact=2011).count(), 2)
        self.assertEqual(Game.objects.filter(season__gt=333).count(), 2)
        self.assertEqual(Game.objects.filter(season__gt__exact=333).count(), 2)
        self.assertEqual(Game.objects.filter(season__year__gt=2010).count(), 2)
        self.assertEqual(Game.objects.filter(season__gt__gt=222).count(), 2)

        # Games played in 2010 and 2011
        self.assertEqual(Game.objects.filter(season__year__in=[2010, 2011]).count(), 5)
        self.assertEqual(Game.objects.filter(season__year__gt=2009).count(), 5)
        self.assertEqual(Game.objects.filter(season__gt__in=[222, 333]).count(), 5)
        self.assertEqual(Game.objects.filter(season__gt__gt=111).count(), 5)

        # Players who played in 2009
        self.assertEqual(Player.objects.filter(games__season__year=2009).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__year__exact=2009).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__gt=111).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__gt__exact=111).distinct().count(), 2)

        # Players who played in 2010
        self.assertEqual(Player.objects.filter(games__season__year=2010).distinct().count(), 1)
        self.assertEqual(Player.objects.filter(games__season__year__exact=2010).distinct().count(), 1)
        self.assertEqual(Player.objects.filter(games__season__gt=222).distinct().count(), 1)
        self.assertEqual(Player.objects.filter(games__season__gt__exact=222).distinct().count(), 1)

        # Players who played in 2011
        self.assertEqual(Player.objects.filter(games__season__year=2011).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__year__exact=2011).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__gt=333).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__year__gt=2010).distinct().count(), 2)
        self.assertEqual(Player.objects.filter(games__season__gt__gt=222).distinct().count(), 2)

    def test_chain_date_time_lookups(self):
        self.assertQuerysetEqual(
            Article.objects.filter(pub_date__month__gt=7),
            ['<Article: Article 5>', '<Article: Article 6>'],
            ordered=False
        )
        self.assertQuerysetEqual(
            Article.objects.filter(pub_date__day__gte=27),
            ['<Article: Article 2>', '<Article: Article 3>',
             '<Article: Article 4>', '<Article: Article 7>'],
            ordered=False
        )
        self.assertQuerysetEqual(
            Article.objects.filter(pub_date__hour__lt=8),
            ['<Article: Article 1>', '<Article: Article 2>',
             '<Article: Article 3>', '<Article: Article 4>',
             '<Article: Article 7>'],
            ordered=False
        )
        self.assertQuerysetEqual(
            Article.objects.filter(pub_date__minute__lte=0),
            ['<Article: Article 1>', '<Article: Article 2>',
             '<Article: Article 3>', '<Article: Article 4>',
             '<Article: Article 5>', '<Article: Article 6>',
             '<Article: Article 7>'],
            ordered=False
        )


class LookupTransactionTests(TransactionTestCase):
    available_apps = ['lookup']

    @ignore_warnings(category=RemovedInDjango20Warning)
    @skipUnless(connection.vendor == 'mysql', 'requires MySQL')
    def test_mysql_lookup_search(self):
        # To use fulltext indexes on MySQL either version 5.6 is needed, or one must use
        # MyISAM tables. Neither of these combinations is currently available on CI, so
        # lets manually create a MyISAM table for Article model.
        with connection.cursor() as cursor:
            cursor.execute(
                "CREATE TEMPORARY TABLE myisam_article ("
                "    id INTEGER PRIMARY KEY AUTO_INCREMENT, "
                "    headline VARCHAR(100) NOT NULL "
                ") ENGINE MYISAM")
            dr = MyISAMArticle.objects.create(headline='Django Reinhardt')
            MyISAMArticle.objects.create(headline='Ringo Star')
            # NOTE: Needs to be created after the article has been saved.
            cursor.execute(
                'CREATE FULLTEXT INDEX myisam_article_ft ON myisam_article (headline)')
            self.assertSequenceEqual(MyISAMArticle.objects.filter(headline__search='Reinhardt'), [dr])