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from __future__ import absolute_import
from django.db import models
from django.test import TestCase
from django.utils import six
from .models import (
First, Third, Parent, Child, Category, Record, Relation, Car, Driver)
class ManyToOneRegressionTests(TestCase):
def test_object_creation(self):
Third.objects.create(id='3', name='An example')
parent = Parent(name='fred')
parent.save()
Child.objects.create(name='bam-bam', parent=parent)
def test_fk_assignment_and_related_object_cache(self):
# Tests of ForeignKey assignment and the related-object cache (see #6886).
p = Parent.objects.create(name="Parent")
c = Child.objects.create(name="Child", parent=p)
# Look up the object again so that we get a "fresh" object.
c = Child.objects.get(name="Child")
p = c.parent
# Accessing the related object again returns the exactly same object.
self.assertTrue(c.parent is p)
# But if we kill the cache, we get a new object.
del c._parent_cache
self.assertFalse(c.parent is p)
# Assigning a new object results in that object getting cached immediately.
p2 = Parent.objects.create(name="Parent 2")
c.parent = p2
self.assertTrue(c.parent is p2)
# Assigning None succeeds if field is null=True.
p.bestchild = None
self.assertTrue(p.bestchild is None)
# bestchild should still be None after saving.
p.save()
self.assertTrue(p.bestchild is None)
# bestchild should still be None after fetching the object again.
p = Parent.objects.get(name="Parent")
self.assertTrue(p.bestchild is None)
# Assigning None fails: Child.parent is null=False.
self.assertRaises(ValueError, setattr, c, "parent", None)
# You also can't assign an object of the wrong type here
self.assertRaises(ValueError, setattr, c, "parent", First(id=1, second=1))
# Nor can you explicitly assign None to Child.parent during object
# creation (regression for #9649).
self.assertRaises(ValueError, Child, name='xyzzy', parent=None)
self.assertRaises(ValueError, Child.objects.create, name='xyzzy', parent=None)
# Trying to assign to unbound attribute raises AttributeError
six.assertRaisesRegex(self, AttributeError, "must be accessed via instance",
Child.parent.__set__, None, p)
# Creation using keyword argument should cache the related object.
p = Parent.objects.get(name="Parent")
c = Child(parent=p)
self.assertTrue(c.parent is p)
# Creation using keyword argument and unsaved related instance (#8070).
p = Parent()
c = Child(parent=p)
self.assertTrue(c.parent is p)
# Creation using attname keyword argument and an id will cause the
# related object to be fetched.
p = Parent.objects.get(name="Parent")
c = Child(parent_id=p.id)
self.assertFalse(c.parent is p)
self.assertEqual(c.parent, p)
def test_multiple_foreignkeys(self):
# Test of multiple ForeignKeys to the same model (bug #7125).
c1 = Category.objects.create(name='First')
c2 = Category.objects.create(name='Second')
c3 = Category.objects.create(name='Third')
r1 = Record.objects.create(category=c1)
r2 = Record.objects.create(category=c1)
r3 = Record.objects.create(category=c2)
r4 = Record.objects.create(category=c2)
r5 = Record.objects.create(category=c3)
r = Relation.objects.create(left=r1, right=r2)
r = Relation.objects.create(left=r3, right=r4)
r = Relation.objects.create(left=r1, right=r3)
r = Relation.objects.create(left=r5, right=r2)
r = Relation.objects.create(left=r3, right=r2)
q1 = Relation.objects.filter(left__category__name__in=['First'], right__category__name__in=['Second'])
self.assertQuerysetEqual(q1, ["<Relation: First - Second>"])
q2 = Category.objects.filter(record__left_set__right__category__name='Second').order_by('name')
self.assertQuerysetEqual(q2, ["<Category: First>", "<Category: Second>"])
p = Parent.objects.create(name="Parent")
c = Child.objects.create(name="Child", parent=p)
self.assertRaises(ValueError, Child.objects.create, name="Grandchild", parent=c)
def test_fk_instantiation_outside_model(self):
# Regression for #12190 -- Should be able to instantiate a FK outside
# of a model, and interrogate its related field.
cat = models.ForeignKey(Category)
self.assertEqual('id', cat.rel.get_related_field().name)
def test_relation_unsaved(self):
# Test that the <field>_set manager does not join on Null value fields (#17541)
Third.objects.create(name='Third 1')
Third.objects.create(name='Third 2')
th = Third(name="testing")
# The object isn't saved an thus the relation field is null - we won't even
# execute a query in this case.
with self.assertNumQueries(0):
self.assertEqual(th.child_set.count(), 0)
th.save()
# Now the model is saved, so we will need to execute an query.
with self.assertNumQueries(1):
self.assertEqual(th.child_set.count(), 0)
def test_related_null_to_field(self):
c1 = Car.objects.create()
c2 = Car.objects.create()
d1 = Driver.objects.create()
self.assertIs(d1.car, None)
with self.assertNumQueries(0):
self.assertEqual(list(c1.drivers.all()), [])
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