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from __future__ import absolute_import
from django.test import TestCase
from .models import Reporter, Article
class ManyToOneNullTests(TestCase):
def setUp(self):
# Create a Reporter.
self.r = Reporter(name='John Smith')
self.r.save()
# Create an Article.
self.a = Article(headline="First", reporter=self.r)
self.a.save()
# Create an Article via the Reporter object.
self.a2 = self.r.article_set.create(headline="Second")
# Create an Article with no Reporter by passing "reporter=None".
self.a3 = Article(headline="Third", reporter=None)
self.a3.save()
# Create another article and reporter
self.r2 = Reporter(name='Paul Jones')
self.r2.save()
self.a4 = self.r2.article_set.create(headline='Fourth')
def test_get_related(self):
self.assertEqual(self.a.reporter.id, self.r.id)
# Article objects have access to their related Reporter objects.
r = self.a.reporter
self.assertEqual(r.id, self.r.id)
def test_created_via_related_set(self):
self.assertEqual(self.a2.reporter.id, self.r.id)
def test_related_set(self):
# Reporter objects have access to their related Article objects.
self.assertQuerysetEqual(self.r.article_set.all(),
['<Article: First>', '<Article: Second>'])
self.assertQuerysetEqual(self.r.article_set.filter(headline__startswith='Fir'),
['<Article: First>'])
self.assertEqual(self.r.article_set.count(), 2)
def test_created_without_related(self):
self.assertEqual(self.a3.reporter, None)
# Need to reget a3 to refresh the cache
a3 = Article.objects.get(pk=self.a3.pk)
self.assertRaises(AttributeError, getattr, a3.reporter, 'id')
# Accessing an article's 'reporter' attribute returns None
# if the reporter is set to None.
self.assertEqual(a3.reporter, None)
# To retrieve the articles with no reporters set, use "reporter__isnull=True".
self.assertQuerysetEqual(Article.objects.filter(reporter__isnull=True),
['<Article: Third>'])
# We can achieve the same thing by filtering for the case where the
# reporter is None.
self.assertQuerysetEqual(Article.objects.filter(reporter=None),
['<Article: Third>'])
# Set the reporter for the Third article
self.assertQuerysetEqual(self.r.article_set.all(),
['<Article: First>', '<Article: Second>'])
self.r.article_set.add(a3)
self.assertQuerysetEqual(self.r.article_set.all(),
['<Article: First>', '<Article: Second>', '<Article: Third>'])
# Remove an article from the set, and check that it was removed.
self.r.article_set.remove(a3)
self.assertQuerysetEqual(self.r.article_set.all(),
['<Article: First>', '<Article: Second>'])
self.assertQuerysetEqual(Article.objects.filter(reporter__isnull=True),
['<Article: Third>'])
def test_remove_from_wrong_set(self):
self.assertQuerysetEqual(self.r2.article_set.all(), ['<Article: Fourth>'])
# Try to remove a4 from a set it does not belong to
self.assertRaises(Reporter.DoesNotExist, self.r.article_set.remove, self.a4)
self.assertQuerysetEqual(self.r2.article_set.all(), ['<Article: Fourth>'])
def test_assign_clear_related_set(self):
# Use descriptor assignment to allocate ForeignKey. Null is legal, so
# existing members of set that are not in the assignment set are set null
self.r2.article_set = [self.a2, self.a3]
self.assertQuerysetEqual(self.r2.article_set.all(),
['<Article: Second>', '<Article: Third>'])
# Clear the rest of the set
self.r.article_set.clear()
self.assertQuerysetEqual(self.r.article_set.all(), [])
self.assertQuerysetEqual(Article.objects.filter(reporter__isnull=True),
['<Article: First>', '<Article: Fourth>'])
def test_clear_efficiency(self):
r = Reporter.objects.create()
for _ in range(3):
r.article_set.create()
with self.assertNumQueries(1):
r.article_set.clear()
self.assertEqual(r.article_set.count(), 0)
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