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Fixed #24495 -- Allowed unsaved model instance assignment check to be bypassed.

This commit is contained in:
Karl Hobley 2015-03-16 19:28:53 +00:00 committed by Tim Graham
parent 02d78bb1a8
commit 81e1a35c36
10 changed files with 136 additions and 5 deletions
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4
django/contrib/contenttypes/fields.py
View File

@ -40,6 +40,8 @@ class GenericForeignKey(object):
one_to_one = False
related_model = None
allow_unsaved_instance_assignment = False
def __init__(self, ct_field='content_type', fk_field='object_id', for_concrete_model=True):
self.ct_field = ct_field
self.fk_field = fk_field
@ -250,7 +252,7 @@ class GenericForeignKey(object):
if value is not None:
ct = self.get_content_type(obj=value)
fk = value._get_pk_val()
if fk is None:
if not self.allow_unsaved_instance_assignment and fk is None:
raise ValueError(
'Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
(value, value._meta.object_name)

5
django/db/models/fields/related.py
View File

@ -513,7 +513,7 @@ class SingleRelatedObjectDescriptor(object):
raise ValueError('Cannot assign "%r": the current database router prevents this relation.' % value)
related_pk = tuple(getattr(instance, field.attname) for field in self.related.field.foreign_related_fields)
if None in related_pk:
if not self.related.field.allow_unsaved_instance_assignment and None in related_pk:
raise ValueError(
'Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
(value, instance._meta.object_name)
@ -684,7 +684,7 @@ class ReverseSingleRelatedObjectDescriptor(object):
else:
for lh_field, rh_field in self.field.related_fields:
pk = value._get_pk_val()
if pk is None:
if not self.field.allow_unsaved_instance_assignment and pk is None:
raise ValueError(
'Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
(value, self.field.rel.to._meta.object_name)
@ -1534,6 +1534,7 @@ class ForeignObject(RelatedField):
one_to_many = False
one_to_one = False
allow_unsaved_instance_assignment = False
requires_unique_target = True
related_accessor_class = ForeignRelatedObjectsDescriptor
rel_class = ForeignObjectRel

7
docs/ref/contrib/contenttypes.txt
View File

@ -299,6 +299,13 @@ model:
is ``True``. This mirrors the ``for_concrete_model`` argument to
:meth:`~django.contrib.contenttypes.models.ContentTypeManager.get_for_model`.
.. attribute:: GenericForeignKey.allow_unsaved_instance_assignment
.. versionadded:: 1.8
Works analogously to :attr:`ForeignKey.allow_unsaved_instance_assignment
<django.db.models.ForeignKey.allow_unsaved_instance_assignment>`.
.. admonition:: Primary key type compatibility
The "object_id" field doesn't have to be the same type as the

32
docs/ref/models/fields.txt
View File

@ -1291,6 +1291,30 @@ The possible values for :attr:`~ForeignKey.on_delete` are found in
If in doubt, leave it to its default of ``True``.
.. attribute:: ForeignKey.allow_unsaved_instance_assignment
.. versionadded:: 1.8
This flag was added for backwards compatibility as older versions of
Django always allowed assigning unsaved model instances.
Django prevents unsaved model instances from being assigned to a
``ForeignKey`` field to prevent accidental data loss (unsaved foreign keys
are silently ignored when saving a model instance).
If you require allowing the assignment of unsaved instances and aren't
concerned about the data loss possibility (e.g. you never save the objects
to the database), you can disable this check by creating a subclass of the
field class and setting its ``allow_unsaved_instance_assignment`` attribute
to ``True``. For example::
class UnsavedForeignKey(models.ForeignKey):
# A ForeignKey which can point to an unsaved object
allow_unsaved_instance_assignment = True
class Book(models.Model):
author = UnsavedForeignKey(Author)
.. _ref-manytomany:
``ManyToManyField``
@ -1388,7 +1412,7 @@ that control how the relationship functions.
* ``<other_model>_id``: the ``id`` of the model that the
``ManyToManyField`` points to.
If the ``ManyToManyField`` points from and to the same model, the following
If the ``ManyToManyField`` points from and to the same model, the following
fields are generated:
* ``id``: the primary key of the relation.
@ -1483,6 +1507,12 @@ that control how the relationship functions.
If in doubt, leave it to its default of ``True``.
.. attribute:: ManyToManyField.allow_unsaved_instance_assignment
.. versionadded:: 1.8
Works analogously to :attr:`ForeignKey.allow_unsaved_instance_assignment`.
:class:`ManyToManyField` does not support :attr:`~Field.validators`.
:attr:`~Field.null` has no effect since there is no way to require a

6
docs/releases/1.8.txt
View File

@ -713,6 +713,12 @@ Now, an error will be raised to prevent data loss::
...
ValueError: Cannot assign "<Author: John>": "Author" instance isn't saved in the database.
If you require allowing the assignment of unsaved instances (the old behavior)
and aren't concerned about the data loss possibility (e.g. you never save the
objects to the database), you can disable this check by using the
:attr:`~django.db.models.ForeignKey.allow_unsaved_instance_assignment`
attribute.
Management commands that only accept positional arguments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

4
docs/topics/db/examples/many_to_one.txt
View File

@ -60,6 +60,10 @@ raises ``ValueError``::
...
ValueError: 'Cannot assign "<Reporter: John Smith>": "Reporter" instance isn't saved in the database.'
If you want to disable the unsaved instance check, you can use the
:attr:`~django.db.models.ForeignKey.allow_unsaved_instance_assignment`
attribute.
.. versionchanged:: 1.8
Previously, assigning unsaved objects did not raise an error and could

4
docs/topics/db/examples/one_to_one.txt
View File

@ -101,6 +101,10 @@ raises ``ValueError``::
...
ValueError: 'Cannot assign "<Restaurant: Demon Dogs the restaurant>": "Restaurant" instance isn't saved in the database.'
If you want to disable the unsaved instance check, you can use the
:attr:`~django.db.models.ForeignKey.allow_unsaved_instance_assignment`
attribute.
.. versionchanged:: 1.8
Previously, assigning unsaved objects did not raise an error and could

27
tests/contenttypes_tests/tests.py
View File

@ -257,6 +257,33 @@ class GenericForeignKeyTests(IsolatedModelsTestCase):
author.save()
model.content_object = author # no error because the instance is saved
def test_unsaved_instance_on_generic_foreign_key_allowed_when_wanted(self):
"""
#24495 - Assigning an unsaved object to a GenericForeignKey
should be allowed when the allow_unsaved_instance_assignment
attribute has been set to True.
"""
class UnsavedGenericForeignKey(GenericForeignKey):
# A GenericForeignKey which can point to an unsaved object
allow_unsaved_instance_assignment = True
class Band(models.Model):
name = models.CharField(max_length=50)
class BandMember(models.Model):
band_ct = models.ForeignKey(ContentType)
band_id = models.PositiveIntegerField()
band = UnsavedGenericForeignKey('band_ct', 'band_id')
first_name = models.CharField(max_length=50)
last_name = models.CharField(max_length=50)
beatles = Band(name='The Beatles')
john = BandMember(first_name='John', last_name='Lennon')
# This should not raise an exception as the GenericForeignKey between
# member and band has allow_unsaved_instance_assignment=True.
john.band = beatles
self.assertEqual(john.band, beatles)
class GenericRelationshipTests(IsolatedModelsTestCase):

25
tests/many_to_one/tests.py
View File

@ -159,6 +159,31 @@ class ManyToOneTests(TestCase):
self.assertFalse(hasattr(self.r2.article_set, 'remove'))
self.assertFalse(hasattr(self.r2.article_set, 'clear'))
def test_assign_unsaved_check_override(self):
"""
#24495 - Assigning an unsaved object to a ForeignKey
should be allowed when the allow_unsaved_instance_assignment
attribute has been set to True.
"""
class UnsavedForeignKey(models.ForeignKey):
# A ForeignKey which can point to an unsaved object
allow_unsaved_instance_assignment = True
class Band(models.Model):
name = models.CharField(max_length=50)
class BandMember(models.Model):
band = UnsavedForeignKey(Band)
first_name = models.CharField(max_length=50)
last_name = models.CharField(max_length=50)
beatles = Band(name='The Beatles')
john = BandMember(first_name='John', last_name='Lennon')
# This should not raise an exception as the ForeignKey between member
# and band has allow_unsaved_instance_assignment=True.
john.band = beatles
self.assertEqual(john.band, beatles)
def test_selects(self):
self.r.article_set.create(headline="John's second story",
pub_date=datetime.date(2005, 7, 29))

27
tests/one_to_one/tests.py
View File

@ -1,6 +1,6 @@
from __future__ import unicode_literals
from django.db import IntegrityError, connection, transaction
from django.db import IntegrityError, connection, models, transaction
from django.test import TestCase
from .models import (
@ -145,6 +145,31 @@ class OneToOneTests(TestCase):
% (bar, p._meta.object_name)):
p.undergroundbar = bar
def test_unsaved_object_check_override(self):
"""
#24495 - Assigning an unsaved object to a OneToOneField
should be allowed when the allow_unsaved_instance_assignment
attribute has been set to True.
"""
class UnsavedOneToOneField(models.OneToOneField):
# A OneToOneField which can point to an unsaved object
allow_unsaved_instance_assignment = True
class Band(models.Model):
name = models.CharField(max_length=50)
class BandManager(models.Model):
band = UnsavedOneToOneField(Band)
first_name = models.CharField(max_length=50)
last_name = models.CharField(max_length=50)
band = Band(name='The Beatles')
manager = BandManager(first_name='Brian', last_name='Epstein')
# This should not raise an exception as the OneToOneField between
# manager and band has allow_unsaved_instance_assignment=True.
manager.band = band
self.assertEqual(manager.band, band)
def test_reverse_relationship_cache_cascade(self):
"""
Regression test for #9023: accessing the reverse relationship shouldn't