Refs #25550 -- Removed support for direct assignment to the reverse side of a related set.

django/db/models/fields/related_descriptors.py

@@ -510,28 +510,16 @@ class ReverseManyToOneDescriptor(object):
         return self.related_manager_cls(instance)
 
     def _get_set_deprecation_msg_params(self):
-        return (  # RemovedInDjango20Warning
+        return (
             'reverse side of a related set',
             self.rel.get_accessor_name(),
         )
 
     def __set__(self, instance, value):
-        """
-        Set the related objects through the reverse relation.
-
-        With the example above, when setting ``parent.children = children``:
-
-        - ``self`` is the descriptor managing the ``children`` attribute
-        - ``instance`` is the ``parent`` instance
-        - ``value`` is the ``children`` sequence on the right of the equal sign
-        """
-        warnings.warn(
-            'Direct assignment to the %s is deprecated due to the implicit '
-            'save() that happens. Use %s.set() instead.' % self._get_set_deprecation_msg_params(),
-            RemovedInDjango20Warning, stacklevel=2,
+        raise TypeError(
+            'Direct assignment to the %s is prohibited. Use %s.set() instead.'
+            % self._get_set_deprecation_msg_params(),
         )
-        manager = self.__get__(instance)
-        manager.set(value)
 
 
 def create_reverse_many_to_one_manager(superclass, rel):
@@ -772,7 +760,7 @@ class ManyToManyDescriptor(ReverseManyToOneDescriptor):
         )
 
     def _get_set_deprecation_msg_params(self):
-        return (  # RemovedInDjango20Warning
+        return (
             '%s side of a many-to-many set' % ('reverse' if self.reverse else 'forward'),
             self.rel.get_accessor_name() if self.reverse else self.field.name,
         )

docs/ref/models/relations.txt

@@ -177,26 +177,3 @@ Related objects reference
        .. versionchanged:: 1.11
 
             The clearing of the prefetched cache described above was added.
-
-Direct Assignment
-=================
-
-A related object set can be replaced in bulk with one operation by assigning a
-new iterable of objects to it::
-
-    >>> new_list = [obj1, obj2, obj3]
-    >>> e.related_set = new_list
-
-If the foreign key relationship has ``null=True``, then the related manager
-will first disassociate any existing objects in the related set before adding
-the contents of ``new_list``. Otherwise the objects in ``new_list`` will be
-added to the existing related object set.
-
-.. deprecated:: 1.10
-
-    Direct assignment is deprecated in favor of the
-    :meth:`~django.db.models.fields.related.RelatedManager.set` method::
-
-        >>> e.related_set.set([obj1, obj2, obj3])
-
-    This prevents confusion about an assignment resulting in an implicit save.

docs/releases/2.0.txt

@@ -321,3 +321,6 @@ these features.
   ``django.template.base.Origin`` are removed.
 
 * The ``makemigrations --exit`` option is removed.
+
+* Support for direct assignment to a reverse foreign key or many-to-many
+  relation is removed.

tests/many_to_many/tests.py

 from __future__ import unicode_literals
 
 from django.db import transaction
-from django.test import TestCase, ignore_warnings
-from django.utils.deprecation import RemovedInDjango20Warning
+from django.test import TestCase
 
 from .models import Article, InheritedArticleA, InheritedArticleB, Publication
 
@@ -400,45 +399,22 @@ class ManyToManyTests(TestCase):
         self.a4.publications.set([], clear=True)
         self.assertQuerysetEqual(self.a4.publications.all(), [])
 
-    def test_assign_forward_deprecation(self):
+    def test_assign_forward(self):
         msg = (
             "Direct assignment to the reverse side of a many-to-many set is "
-            "deprecated due to the implicit save() that happens. Use "
-            "article_set.set() instead."
+            "prohibited. Use article_set.set() instead."
         )
-        with self.assertRaisesMessage(RemovedInDjango20Warning, msg):
+        with self.assertRaisesMessage(TypeError, msg):
             self.p2.article_set = [self.a4, self.a3]
 
-    def test_assign_reverse_deprecation(self):
+    def test_assign_reverse(self):
         msg = (
             "Direct assignment to the forward side of a many-to-many "
-            "set is deprecated due to the implicit save() that happens. Use "
-            "publications.set() instead."
+            "set is prohibited. Use publications.set() instead."
         )
-        with self.assertRaisesMessage(RemovedInDjango20Warning, msg):
+        with self.assertRaisesMessage(TypeError, msg):
             self.a1.publications = [self.p1, self.p2]
 
-    @ignore_warnings(category=RemovedInDjango20Warning)
-    def test_assign_deprecated(self):
-        self.p2.article_set = [self.a4, self.a3]
-        self.assertQuerysetEqual(
-            self.p2.article_set.all(),
-            [
-                '<Article: NASA finds intelligent life on Earth>',
-                '<Article: Oxygen-free diet works wonders>',
-            ]
-        )
-        self.assertQuerysetEqual(self.a4.publications.all(), ['<Publication: Science News>'])
-        self.a4.publications = [self.p3.id]
-        self.assertQuerysetEqual(self.p2.article_set.all(), ['<Article: NASA finds intelligent life on Earth>'])
-        self.assertQuerysetEqual(self.a4.publications.all(), ['<Publication: Science Weekly>'])
-
-        # An alternate to calling clear() is to assign the empty set
-        self.p2.article_set = []
-        self.assertQuerysetEqual(self.p2.article_set.all(), [])
-        self.a4.publications = []
-        self.assertQuerysetEqual(self.a4.publications.all(), [])
-
     def test_assign(self):
         # Relation sets can be assigned using set().
         self.p2.article_set.set([self.a4, self.a3])

tests/many_to_one/tests.py

@@ -115,10 +115,9 @@ class ManyToOneTests(TestCase):
     def test_reverse_assignment_deprecation(self):
         msg = (
             "Direct assignment to the reverse side of a related set is "
-            "deprecated due to the implicit save() that happens. Use "
-            "article_set.set() instead."
+            "prohibited. Use article_set.set() instead."
         )
-        with self.assertRaisesMessage(RemovedInDjango20Warning, msg):
+        with self.assertRaisesMessage(TypeError, msg):
             self.r2.article_set = []
 
     def test_assign(self):