Refs #7098 -- Deprecated passing raw column aliases to order_by().

Now that order_by() has expression support passing RawSQL() can achieve
the same result.

This was also already supported through QuerySet.extra(order_by) for
years but this API is more or less deprecated at this point.

django/db/models/sql/query.py

@@ -1895,7 +1895,16 @@ class Query(BaseExpression):
         """
         errors = []
         for item in ordering:
-            if not hasattr(item, 'resolve_expression') and not ORDER_PATTERN.match(item):
+            if isinstance(item, str) and ORDER_PATTERN.match(item):
+                if '.' in item:
+                    warnings.warn(
+                        'Passing column raw column aliases to order_by() is '
+                        'deprecated. Wrap %r in a RawSQL expression before '
+                        'passing it to order_by().' % item,
+                        category=RemovedInDjango40Warning,
+                        stacklevel=3,
+                    )
+            elif not hasattr(item, 'resolve_expression'):
                 errors.append(item)
             if getattr(item, 'contains_aggregate', False):
                 raise FieldError(

docs/internals/deprecation.txt

@@ -69,6 +69,9 @@ details on these changes.
 * ``django.views.generic.TemplateView`` will no longer pass URL kwargs directly
   to the ``context``.
 
+* Support for passing raw column aliases to ``QuerySet.order_by()`` will be
+  removed.
+
 See the :ref:`Django 3.1 release notes <deprecated-features-3.1>` for more
 details on these changes.
 

docs/releases/3.1.txt

@@ -678,6 +678,10 @@ Miscellaneous
   :class:`~django.views.generic.base.TemplateView` is deprecated. Reference
   them in the template with ``view.kwargs`` instead.
 
+* Passing raw column aliases to :meth:`.QuerySet.order_by` is deprecated. The
+  same result can be achieved by passing aliases in a
+  :class:`~django.db.models.expressions.RawSQL` instead beforehand.
+
 .. _removed-features-3.1:
 
 Features removed in 3.1

tests/queries/tests.py

@@ -7,10 +7,12 @@ from operator import attrgetter
 from django.core.exceptions import EmptyResultSet, FieldError
 from django.db import DEFAULT_DB_ALIAS, connection
 from django.db.models import Count, Exists, F, OuterRef, Q
+from django.db.models.expressions import RawSQL
 from django.db.models.sql.constants import LOUTER
 from django.db.models.sql.where import NothingNode, WhereNode
 from django.test import SimpleTestCase, TestCase, skipUnlessDBFeature
-from django.test.utils import CaptureQueriesContext
+from django.test.utils import CaptureQueriesContext, ignore_warnings
+from django.utils.deprecation import RemovedInDjango40Warning
 
 from .models import (
     FK1, Annotation, Article, Author, BaseA, Book, CategoryItem,
@@ -609,14 +611,36 @@ class Queries1Tests(TestCase):
             ['datetime.datetime(2007, 12, 19, 0, 0)']
         )
 
+    @ignore_warnings(category=RemovedInDjango40Warning)
     def test_ticket7098(self):
-        # Make sure semi-deprecated ordering by related models syntax still
-        # works.
         self.assertSequenceEqual(
             Item.objects.values('note__note').order_by('queries_note.note', 'id'),
             [{'note__note': 'n2'}, {'note__note': 'n3'}, {'note__note': 'n3'}, {'note__note': 'n3'}]
         )
 
+    def test_order_by_rawsql(self):
+        self.assertSequenceEqual(
+            Item.objects.values('note__note').order_by(
+                RawSQL('queries_note.note', ()),
+                'id',
+            ),
+            [
+                {'note__note': 'n2'},
+                {'note__note': 'n3'},
+                {'note__note': 'n3'},
+                {'note__note': 'n3'},
+            ],
+        )
+
+    def test_order_by_raw_column_alias_warning(self):
+        msg = (
+            "Passing column raw column aliases to order_by() is deprecated. "
+            "Wrap 'queries_author.name' in a RawSQL expression before "
+            "passing it to order_by()."
+        )
+        with self.assertRaisesMessage(RemovedInDjango40Warning, msg):
+            Item.objects.values('creator__name').order_by('queries_author.name')
+
     def test_ticket7096(self):
         # Make sure exclude() with multiple conditions continues to work.
         self.assertQuerysetEqual(