from datetime import datetime
from django.db.models import Avg
from django.test import TestCase
from .models import Article, Comment, IndexErrorArticle, Person
class EarliestOrLatestTests(TestCase):
"""Tests for the earliest() and latest() objects methods"""
@classmethod
def setUpClass(cls):
super().setUpClass()
cls._article_get_latest_by = Article._meta.get_latest_by
def tearDown(self):
Article._meta.get_latest_by = self._article_get_latest_by
def test_earliest(self):
# Because no Articles exist yet, earliest() raises ArticleDoesNotExist.
with self.assertRaises(Article.DoesNotExist):
Article.objects.earliest()
a1 = Article.objects.create(
headline="Article 1",
pub_date=datetime(2005, 7, 26),
expire_date=datetime(2005, 9, 1),
)
a2 = Article.objects.create(
headline="Article 2",
pub_date=datetime(2005, 7, 27),
expire_date=datetime(2005, 7, 28),
)
a3 = Article.objects.create(
headline="Article 3",
pub_date=datetime(2005, 7, 28),
expire_date=datetime(2005, 8, 27),
)
a4 = Article.objects.create(
headline="Article 4",
pub_date=datetime(2005, 7, 28),
expire_date=datetime(2005, 7, 30),
)
# Get the earliest Article.
self.assertEqual(Article.objects.earliest(), a1)
# Get the earliest Article that matches certain filters.
self.assertEqual(
Article.objects.filter(pub_date__gt=datetime(2005, 7, 26)).earliest(), a2
)
# Pass a custom field name to earliest() to change the field that's used
# to determine the earliest object.
self.assertEqual(Article.objects.earliest("expire_date"), a2)
self.assertEqual(
Article.objects.filter(pub_date__gt=datetime(2005, 7, 26)).earliest(
"expire_date"
),
a2,
)
# earliest() overrides any other ordering specified on the query.
# Refs #11283.
self.assertEqual(Article.objects.order_by("id").earliest(), a1)
# Error is raised if the user forgot to add a get_latest_by
# in the Model.Meta
Article.objects.model._meta.get_latest_by = None
with self.assertRaisesMessage(
ValueError,
"earliest() and latest() require either fields as positional "
"arguments or 'get_latest_by' in the model's Meta.",
):
Article.objects.earliest()
# Earliest publication date, earliest expire date.
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 28)).earliest(
"pub_date", "expire_date"
),
a4,
)
# Earliest publication date, latest expire date.
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 28)).earliest(
"pub_date", "-expire_date"
),
a3,
)
# Meta.get_latest_by may be a tuple.
Article.objects.model._meta.get_latest_by = ("pub_date", "expire_date")
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 28)).earliest(), a4
)
def test_earliest_sliced_queryset(self):
msg = "Cannot change a query once a slice has been taken."
with self.assertRaisesMessage(TypeError, msg):
Article.objects.all()[0:5].earliest()
def test_latest(self):
# Because no Articles exist yet, latest() raises ArticleDoesNotExist.
with self.assertRaises(Article.DoesNotExist):
Article.objects.latest()
a1 = Article.objects.create(
headline="Article 1",
pub_date=datetime(2005, 7, 26),
expire_date=datetime(2005, 9, 1),
)
a2 = Article.objects.create(
headline="Article 2",
pub_date=datetime(2005, 7, 27),
expire_date=datetime(2005, 7, 28),
)
a3 = Article.objects.create(
headline="Article 3",
pub_date=datetime(2005, 7, 27),
expire_date=datetime(2005, 8, 27),
)
a4 = Article.objects.create(
headline="Article 4",
pub_date=datetime(2005, 7, 28),
expire_date=datetime(2005, 7, 30),
)
# Get the latest Article.
self.assertEqual(Article.objects.latest(), a4)
# Get the latest Article that matches certain filters.
self.assertEqual(
Article.objects.filter(pub_date__lt=datetime(2005, 7, 27)).latest(), a1
)
# Pass a custom field name to latest() to change the field that's used
# to determine the latest object.
self.assertEqual(Article.objects.latest("expire_date"), a1)
self.assertEqual(
Article.objects.filter(pub_date__gt=datetime(2005, 7, 26)).latest(
"expire_date"
),
a3,
)
# latest() overrides any other ordering specified on the query (#11283).
self.assertEqual(Article.objects.order_by("id").latest(), a4)
# Error is raised if get_latest_by isn't in Model.Meta.
Article.objects.model._meta.get_latest_by = None
with self.assertRaisesMessage(
ValueError,
"earliest() and latest() require either fields as positional "
"arguments or 'get_latest_by' in the model's Meta.",
):
Article.objects.latest()
# Latest publication date, latest expire date.
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 27)).latest(
"pub_date", "expire_date"
),
a3,
)
# Latest publication date, earliest expire date.
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 27)).latest(
"pub_date", "-expire_date"
),
a2,
)
# Meta.get_latest_by may be a tuple.
Article.objects.model._meta.get_latest_by = ("pub_date", "expire_date")
self.assertEqual(
Article.objects.filter(pub_date=datetime(2005, 7, 27)).latest(), a3
)
def test_latest_sliced_queryset(self):
msg = "Cannot change a query once a slice has been taken."
with self.assertRaisesMessage(TypeError, msg):
Article.objects.all()[0:5].latest()
def test_latest_manual(self):
# You can still use latest() with a model that doesn't have
# "get_latest_by" set -- just pass in the field name manually.
Person.objects.create(name="Ralph", birthday=datetime(1950, 1, 1))
p2 = Person.objects.create(name="Stephanie", birthday=datetime(1960, 2, 3))
msg = (
"earliest() and latest() require either fields as positional arguments "
"or 'get_latest_by' in the model's Meta."
)
with self.assertRaisesMessage(ValueError, msg):
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))
self.assertEqual(Person.objects.first(), p1)
self.assertEqual(Person.objects.order_by("name").first(), p2)
self.assertEqual(
Person.objects.filter(birthday__lte=datetime(1955, 1, 1)).first(), p1
)
self.assertIsNone(
Person.objects.filter(birthday__lte=datetime(1940, 1, 1)).first()
)
def test_last(self):
p1 = Person.objects.create(name="Alice", birthday=datetime(1950, 1, 1))
p2 = Person.objects.create(name="Bob", birthday=datetime(1960, 2, 3))
# Note: by default PK ordering.
self.assertEqual(Person.objects.last(), p2)
self.assertEqual(Person.objects.order_by("-name").last(), p1)
self.assertEqual(
Person.objects.filter(birthday__lte=datetime(1955, 1, 1)).last(), p1
)
self.assertIsNone(
Person.objects.filter(birthday__lte=datetime(1940, 1, 1)).last()
)
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.
with self.assertRaises(IndexError):
IndexErrorArticle.objects.all()[:10:2]
with self.assertRaises(IndexError):
IndexErrorArticle.objects.first()
with self.assertRaises(IndexError):
IndexErrorArticle.objects.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()
def test_first_last_unordered_qs_aggregation_error(self):
a1 = Article.objects.create(
headline="Article 1",
pub_date=datetime(2005, 7, 26),
expire_date=datetime(2005, 9, 1),
)
Comment.objects.create(article=a1, likes_count=5)
qs = Comment.objects.values("article").annotate(avg_likes=Avg("likes_count"))
msg = (
"Cannot use QuerySet.%s() on an unordered queryset performing aggregation. "
"Add an ordering with order_by()."
)
with self.assertRaisesMessage(TypeError, msg % "first"):
qs.first()
with self.assertRaisesMessage(TypeError, msg % "last"):
qs.last()