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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@ -223,6 +223,11 @@ class GenericForeignKey(object):
if value is not None: if value is not None:
ct = self.get_content_type(obj=value) ct = self.get_content_type(obj=value)
fk = value._get_pk_val() 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.ct_field, ct)
setattr(instance, self.fk_field, fk) setattr(instance, self.fk_field, fk)

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@ -617,13 +617,20 @@ class ReverseSingleRelatedObjectDescriptor(object):
if related is not None: if related is not None:
setattr(related, self.field.related.get_cache_name(), 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:
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) 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 # 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 caches now, too. This avoids another db hit if you get the
# object you just set. # object you just set.

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@ -218,19 +218,47 @@ Backwards incompatible changes in 1.8
deprecation timeline for a given feature, its removal may appear as a deprecation timeline for a given feature, its removal may appear as a
backwards incompatible change. backwards incompatible change.
* Some operations on related objects such as Related object operations are run in a transaction
: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 Some operations on related objects such as
from these methods are now executed within the method's transaction and :meth:`~django.db.models.fields.related.RelatedManager.add()` or
any exception in a signal handler will prevent the whole operation. :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 Miscellaneous
~~~~~~~~~~~~~ ~~~~~~~~~~~~~

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@ -52,6 +52,21 @@ Create an Article::
>>> a.reporter >>> a.reporter
<Reporter: John Smith> <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:: Article objects have access to their related Reporter objects::
>>> r = a.reporter >>> r = a.reporter

View File

@ -89,6 +89,25 @@ Set the place back again, using assignment in the reverse direction::
>>> p1.restaurant >>> p1.restaurant
<Restaurant: Demon Dogs the 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 Restaurant.objects.all() just returns the Restaurants, not the Places. Note
that there are two restaurants - Ace Hardware the Restaurant was created in the that there are two restaurants - Ace Hardware the Restaurant was created in the
call to r.place = p2:: call to r.place = p2::

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

View File

@ -209,6 +209,27 @@ class GenericForeignKeyTests(IsolatedModelsTestCase):
errors = checks.run_checks() errors = checks.run_checks()
self.assertEqual(errors, ['performed!']) 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): class GenericRelationshipTests(IsolatedModelsTestCase):

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@ -66,8 +66,10 @@ class ManyToOneRegressionTests(TestCase):
# Creation using keyword argument and unsaved related instance (#8070). # Creation using keyword argument and unsaved related instance (#8070).
p = Parent() p = Parent()
c = Child(parent=p) with self.assertRaisesMessage(ValueError,
self.assertTrue(c.parent is p) '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 # Creation using attname keyword argument and an id will cause the
# related object to be fetched. # related object to be fetched.

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@ -476,8 +476,6 @@ class QueryTestCase(TestCase):
dive = Book.objects.using('other').create(title="Dive into Python", dive = Book.objects.using('other').create(title="Dive into Python",
published=datetime.date(2009, 5, 4)) 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 # Set a foreign key with an object from a different database
with self.assertRaises(ValueError): with self.assertRaises(ValueError):
dive.editor = marty dive.editor = marty
@ -492,54 +490,6 @@ class QueryTestCase(TestCase):
with transaction.atomic(using='default'): with transaction.atomic(using='default'):
marty.edited.add(dive) 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): def test_foreign_key_deletion(self):
"Cascaded deletions of Foreign Key relations issue queries on the right database" "Cascaded deletions of Foreign Key relations issue queries on the right database"
mark = Person.objects.using('other').create(name="Mark Pilgrim") 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 # old object comes from 'other', so the new object is set to use the
# source of 'other'... # source of 'other'...
self.assertEqual(dive._state.db, 'other') self.assertEqual(dive._state.db, 'other')
chris.save()
dive.editor = chris dive.editor = chris
html5.editor = mark html5.editor = mark

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

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@ -3,7 +3,7 @@ from __future__ import unicode_literals
from django.db import transaction, IntegrityError from django.db import transaction, IntegrityError
from django.test import TestCase from django.test import TestCase
from .models import (Place, Restaurant, Waiter, ManualPrimaryKey, RelatedModel, from .models import (Place, Restaurant, Bar, Waiter, ManualPrimaryKey, RelatedModel,
MultiModel) MultiModel)
@ -128,3 +128,20 @@ class OneToOneTests(TestCase):
with self.assertRaises(IntegrityError): with self.assertRaises(IntegrityError):
with transaction.atomic(): with transaction.atomic():
mm.save() 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

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