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Fixed #10811 -- Made assigning unsaved objects to FK, O2O, and GFK raise ValueError. 

This prevents silent data loss.

Thanks Aymeric Augustin for the initial patch and Loic Bistuer for the review.
This commit is contained in:
Anubhav Joshi 2014-05-19 14:15:55 +05:30 committed by Tim Graham
parent 4f72e5f03a
commit 5643a3b51b
12 changed files with 141 additions and 76 deletions
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5
django/contrib/contenttypes/fields.py
View File

@ -223,6 +223,11 @@ class GenericForeignKey(object):
if value is not None:
ct = self.get_content_type(obj=value)
fk = value._get_pk_val()
if fk is None:
raise ValueError(
'Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
(value, value._meta.object_name)
)
setattr(instance, self.ct_field, ct)
setattr(instance, self.fk_field, fk)

15
django/db/models/fields/related.py
View File

@ -617,13 +617,20 @@ class ReverseSingleRelatedObjectDescriptor(object):
if related is not None:
setattr(related, self.field.related.get_cache_name(), None)
# Set the value of the related field
for lh_field, rh_field in self.field.related_fields:
try:
setattr(instance, lh_field.attname, getattr(value, rh_field.attname))
except AttributeError:
setattr(instance, lh_field.attname, None)
# Set the values of the related field.
else:
for lh_field, rh_field in self.field.related_fields:
val = getattr(value, rh_field.attname)
if val is None:
raise ValueError(
'Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
(value, self.field.rel.to._meta.object_name)
)
setattr(instance, lh_field.attname, val)
# Since we already know what the related object is, seed the related
# object caches now, too. This avoids another db hit if you get the
# object you just set.

52
docs/releases/1.8.txt
View File

@ -218,19 +218,47 @@ Backwards incompatible changes in 1.8
deprecation timeline for a given feature, its removal may appear as a
backwards incompatible change.
* Some operations on related objects such as
:meth:`~django.db.models.fields.related.RelatedManager.add()` or
:ref:`direct assignment<direct-assignment>` ran multiple data modifying
queries without wrapping them in transactions. To reduce the risk of data
corruption, all data modifying methods that affect multiple related objects
(i.e. ``add()``, ``remove()``, ``clear()``, and
:ref:`direct assignment<direct-assignment>`) now perform their data modifying
queries from within a transaction, provided your database supports
transactions.
Related object operations are run in a transaction
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This has one backwards incompatible side effect, signal handlers triggered
from these methods are now executed within the method's transaction and
any exception in a signal handler will prevent the whole operation.
Some operations on related objects such as
:meth:`~django.db.models.fields.related.RelatedManager.add()` or
:ref:`direct assignment<direct-assignment>` ran multiple data modifying
queries without wrapping them in transactions. To reduce the risk of data
corruption, all data modifying methods that affect multiple related objects
(i.e. ``add()``, ``remove()``, ``clear()``, and :ref:`direct assignment
<direct-assignment>`) now perform their data modifying queries from within a
transaction, provided your database supports transactions.
This has one backwards incompatible side effect, signal handlers triggered from
these methods are now executed within the method's transaction and any
exception in a signal handler will prevent the whole operation.
Unassigning unsaved objects to relations raises an error
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Assigning unsaved objects to a :class:`~django.db.models.ForeignKey`,
:class:`~django.contrib.contenttypes.fields.GenericForeignKey`, and
:class:`~django.db.models.OneToOneField` now raises a :exc:`ValueError`.
Previously, the assignment of an unsaved object would be silently ignored.
For example::
>>> book = Book.objects.create(name="Django")
>>> book.author = Author(name="John")
>>> book.author.save()
>>> book.save()
>>> Book.objects.get(name="Django")
>>> book.author
>>>
Now, an error will be raised to prevent data loss::
>>> book.author = Author(name="john")
Traceback (most recent call last):
...
ValueError: Cannot assign "<Author: John>": "Author" instance isn't saved in the database.
Miscellaneous
~~~~~~~~~~~~~

15
docs/topics/db/examples/many_to_one.txt
View File

@ -52,6 +52,21 @@ Create an Article::
>>> a.reporter
<Reporter: John Smith>
Note that you must save an object before it can be assigned to a foreign key
relationship. For example, creating an ``Article`` with unsaved ``Reporter``
raises ``ValueError``::
>>> r3 = Reporter(first_name='John', last_name='Smith', email='john@example.com')
>>> Article(headline="This is a test", pub_date=date(2005, 7, 27), reporter=r3)
Traceback (most recent call last):
...
ValueError: 'Cannot assign "<Reporter: John Smith>": "Reporter" instance isn't saved in the database.'
.. versionchanged:: 1.8
Previously, assigning unsaved objects did not raise an error and could
result in silent data loss.
Article objects have access to their related Reporter objects::
>>> r = a.reporter

19
docs/topics/db/examples/one_to_one.txt
View File

@ -89,6 +89,25 @@ Set the place back again, using assignment in the reverse direction::
>>> p1.restaurant
<Restaurant: Demon Dogs the restaurant>
Note that you must save an object before it can be assigned to a one-to-one
relationship. For example, creating an ``Restaurant`` with unsaved ``Place``
raises ``ValueError``::
>>> p3 = Place(name='Demon Dogs', address='944 W. Fullerton')
>>> Restaurant(place=p3, serves_hot_dogs=True, serves_pizza=False)
Traceback (most recent call last):
...
ValueError: 'Cannot assign "<Place: Demon Dogs>": "Place" instance isn't saved in the database.'
>>> p.restaurant = Restaurant(place=p, serves_hot_dogs=True, serves_pizza=False)
Traceback (most recent call last):
...
ValueError: 'Cannot assign "<Restaurant: Demon Dogs the restaurant>": "Restaurant" instance isn't saved in the database.'
.. versionchanged:: 1.8
Previously, assigning unsaved objects did not raise an error and could
result in silent data loss.
Restaurant.objects.all() just returns the Restaurants, not the Places. Note
that there are two restaurants - Ace Hardware the Restaurant was created in the
call to r.place = p2::

3
tests/admin_util/tests.py
View File

@ -109,8 +109,9 @@ class UtilTests(SimpleTestCase):
simple_function = lambda obj: SIMPLE_FUNCTION
site_obj = Site.objects.create(domain=SITE_NAME)
article = Article(
site=Site(domain=SITE_NAME),
site=site_obj,
title=TITLE_TEXT,
created=CREATED_DATE,
)

21
tests/contenttypes_tests/tests.py
View File

@ -209,6 +209,27 @@ class GenericForeignKeyTests(IsolatedModelsTestCase):
errors = checks.run_checks()
self.assertEqual(errors, ['performed!'])
def test_unsaved_instance_on_generic_foreign_key(self):
"""
#10811 -- Assigning an unsaved object to GenericForeignKey
should raise an exception.
"""
class Model(models.Model):
content_type = models.ForeignKey(ContentType, null=True)
object_id = models.PositiveIntegerField(null=True)
content_object = GenericForeignKey('content_type', 'object_id')
author = Author(name='Author')
model = Model()
model.content_object = None # no error here as content_type allows None
with self.assertRaisesMessage(ValueError,
'Cannot assign "%r": "%s" instance isn\'t saved in the database.'
% (author, author._meta.object_name)):
model.content_object = author # raised ValueError here as author is unsaved
author.save()
model.content_object = author # no error because the instance is saved
class GenericRelationshipTests(IsolatedModelsTestCase):

6
tests/many_to_one_regress/tests.py
View File

@ -66,8 +66,10 @@ class ManyToOneRegressionTests(TestCase):
# Creation using keyword argument and unsaved related instance (#8070).
p = Parent()
c = Child(parent=p)
self.assertTrue(c.parent is p)
with self.assertRaisesMessage(ValueError,
'Cannot assign "%r": "%s" instance isn\'t saved in the database.'
% (p, Child.parent.field.rel.to._meta.object_name)):
Child(parent=p)
# Creation using attname keyword argument and an id will cause the
# related object to be fetched.

51
tests/multiple_database/tests.py
View File

@ -476,8 +476,6 @@ class QueryTestCase(TestCase):
dive = Book.objects.using('other').create(title="Dive into Python",
published=datetime.date(2009, 5, 4))
mark = Person.objects.using('other').create(name="Mark Pilgrim")
# Set a foreign key with an object from a different database
with self.assertRaises(ValueError):
dive.editor = marty
@ -492,54 +490,6 @@ class QueryTestCase(TestCase):
with transaction.atomic(using='default'):
marty.edited.add(dive)
# BUT! if you assign a FK object when the base object hasn't
# been saved yet, you implicitly assign the database for the
# base object.
chris = Person(name="Chris Mills")
html5 = Book(title="Dive into HTML5", published=datetime.date(2010, 3, 15))
# initially, no db assigned
self.assertEqual(chris._state.db, None)
self.assertEqual(html5._state.db, None)
# old object comes from 'other', so the new object is set to use 'other'...
dive.editor = chris
html5.editor = mark
self.assertEqual(chris._state.db, 'other')
self.assertEqual(html5._state.db, 'other')
# ... but it isn't saved yet
self.assertEqual(list(Person.objects.using('other').values_list('name', flat=True)),
['Mark Pilgrim'])
self.assertEqual(list(Book.objects.using('other').values_list('title', flat=True)),
['Dive into Python'])
# When saved (no using required), new objects goes to 'other'
chris.save()
html5.save()
self.assertEqual(list(Person.objects.using('default').values_list('name', flat=True)),
['Marty Alchin'])
self.assertEqual(list(Person.objects.using('other').values_list('name', flat=True)),
['Chris Mills', 'Mark Pilgrim'])
self.assertEqual(list(Book.objects.using('default').values_list('title', flat=True)),
['Pro Django'])
self.assertEqual(list(Book.objects.using('other').values_list('title', flat=True)),
['Dive into HTML5', 'Dive into Python'])
# This also works if you assign the FK in the constructor
water = Book(title="Dive into Water", published=datetime.date(2001, 1, 1), editor=mark)
self.assertEqual(water._state.db, 'other')
# ... but it isn't saved yet
self.assertEqual(list(Book.objects.using('default').values_list('title', flat=True)),
['Pro Django'])
self.assertEqual(list(Book.objects.using('other').values_list('title', flat=True)),
['Dive into HTML5', 'Dive into Python'])
# When saved, the new book goes to 'other'
water.save()
self.assertEqual(list(Book.objects.using('default').values_list('title', flat=True)),
['Pro Django'])
self.assertEqual(list(Book.objects.using('other').values_list('title', flat=True)),
['Dive into HTML5', 'Dive into Python', 'Dive into Water'])
def test_foreign_key_deletion(self):
"Cascaded deletions of Foreign Key relations issue queries on the right database"
mark = Person.objects.using('other').create(name="Mark Pilgrim")
@ -1148,6 +1098,7 @@ class RouterTestCase(TestCase):
# old object comes from 'other', so the new object is set to use the
# source of 'other'...
self.assertEqual(dive._state.db, 'other')
chris.save()
dive.editor = chris
html5.editor = mark

4
tests/one_to_one/models.py
View File

@ -30,6 +30,10 @@ class Restaurant(models.Model):
return "%s the restaurant" % self.place.name
class Bar(models.Model):
place = models.OneToOneField(Place, null=True)
@python_2_unicode_compatible
class Waiter(models.Model):
restaurant = models.ForeignKey(Restaurant)

19
tests/one_to_one/tests.py
View File

@ -3,7 +3,7 @@ from __future__ import unicode_literals
from django.db import transaction, IntegrityError
from django.test import TestCase
from .models import (Place, Restaurant, Waiter, ManualPrimaryKey, RelatedModel,
from .models import (Place, Restaurant, Bar, Waiter, ManualPrimaryKey, RelatedModel,
MultiModel)
@ -128,3 +128,20 @@ class OneToOneTests(TestCase):
with self.assertRaises(IntegrityError):
with transaction.atomic():
mm.save()
def test_unsaved_object(self):
"""
#10811 -- Assigning an unsaved object to a OneToOneField
should raise an exception.
"""
place = Place(name='User', address='London')
with self.assertRaisesMessage(ValueError,
'Cannot assign "%r": "%s" instance isn\'t saved in the database.'
% (place, Restaurant.place.field.rel.to._meta.object_name)):
Restaurant.objects.create(place=place, serves_hot_dogs=True, serves_pizza=False)
bar = Bar()
p = Place(name='User', address='London')
with self.assertRaisesMessage(ValueError,
'Cannot assign "%r": "%s" instance isn\'t saved in the database.'
% (bar, p._meta.object_name)):
p.bar = bar

5
tests/one_to_one_regress/tests.py
View File

@ -96,11 +96,6 @@ class OneToOneRegressionTests(TestCase):
r = Restaurant(place=p)
self.assertTrue(r.place is p)
# Creation using keyword argument and unsaved related instance (#8070).
p = Place()
r = Restaurant(place=p)
self.assertTrue(r.place is p)
# Creation using attname keyword argument and an id will cause the related
# object to be fetched.
p = Place.objects.get(name="Demon Dogs")