[3.0.x] Fixed #31150 -- Included subqueries that reference related fields in GROUP BY clauses.

Thanks Johannes Hoppe for the report.

Regression in fb3f034f1c63160c0ff13c609acd01c18be12f80.

Co-authored-by: Simon Charette <charette.s@gmail.com>

Backport of 7b8fa1653fde578ab3a496d9974ab1d4261b8b26 from master

1 files changed, 14 insertions, 1 deletions

diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 3adec334f7..2733fbada9 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -6,6 +6,7 @@ from decimal import Decimal
 from django.core.exceptions import EmptyResultSet, FieldError
 from django.db import connection
 from django.db.models import fields
+from django.db.models.constants import LOOKUP_SEP
 from django.db.models.query_utils import Q
 from django.db.utils import NotSupportedError
 from django.utils.deconstruct import deconstructible
@@ -558,6 +559,14 @@ class ResolvedOuterRef(F):
             'only be used in a subquery.'
         )
 
+    def resolve_expression(self, *args, **kwargs):
+        col = super().resolve_expression(*args, **kwargs)
+        # FIXME: Rename possibly_multivalued to multivalued and fix detection
+        # for non-multivalued JOINs (e.g. foreign key fields). This should take
+        # into account only many-to-many and one-to-many relationships.
+        col.possibly_multivalued = LOOKUP_SEP in self.name
+        return col
+
     def relabeled_clone(self, relabels):
         return self
 
@@ -744,6 +753,7 @@ class Random(Expression):
 class Col(Expression):
 
     contains_column_references = True
+    possibly_multivalued = False
 
     def __init__(self, alias, target, output_field=None):
         if output_field is None:
@@ -1068,7 +1078,10 @@ class Subquery(Expression):
     def get_group_by_cols(self, alias=None):
         if alias:
             return [Ref(alias, self)]
-        return self.query.get_external_cols()
+        external_cols = self.query.get_external_cols()
+        if any(col.possibly_multivalued for col in external_cols):
+            return [self]
+        return external_cols
 
 
 class Exists(Subquery):