Fixed #35241 -- Cached model's full parent list.

co-authored-by: Keryn Knight <keryn@kerynknight.com>
co-authored-by: Natalia <124304+nessita@users.noreply.github.com>
co-authored-by: David Smith <smithdc@gmail.com>
co-authored-by: Paolo Melchiorre <paolo@melchiorre.org>

10 files changed, 41 insertions, 33 deletions

diff --git a/django/contrib/admin/helpers.py b/django/contrib/admin/helpers.py
index 90ca7affc8..c4613fa24e 100644
--- a/django/contrib/admin/helpers.py
+++ b/django/contrib/admin/helpers.py
@@ -504,7 +504,7 @@ class InlineAdminForm(AdminForm):
             # in parents.)
             any(
                 parent._meta.auto_field or not parent._meta.model._meta.pk.editable
-                for parent in self.form._meta.model._meta.get_parent_list()
+                for parent in self.form._meta.model._meta.all_parents
             )
         )
 
diff --git a/django/db/models/base.py b/django/db/models/base.py
index 75328e0749..9dda7cbff9 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -1368,7 +1368,7 @@ class Model(AltersData, metaclass=ModelBase):
         constraints = []
         if include_meta_constraints:
             constraints = [(self.__class__, self._meta.total_unique_constraints)]
-        for parent_class in self._meta.get_parent_list():
+        for parent_class in self._meta.all_parents:
             if parent_class._meta.unique_together:
                 unique_togethers.append(
                     (parent_class, parent_class._meta.unique_together)
@@ -1397,7 +1397,7 @@ class Model(AltersData, metaclass=ModelBase):
         # the list of checks.
 
         fields_with_class = [(self.__class__, self._meta.local_fields)]
-        for parent_class in self._meta.get_parent_list():
+        for parent_class in self._meta.all_parents:
             fields_with_class.append((parent_class, parent_class._meta.local_fields))
 
         for model_class, fields in fields_with_class:
@@ -1546,7 +1546,7 @@ class Model(AltersData, metaclass=ModelBase):
 
     def get_constraints(self):
         constraints = [(self.__class__, self._meta.constraints)]
-        for parent_class in self._meta.get_parent_list():
+        for parent_class in self._meta.all_parents:
             if parent_class._meta.constraints:
                 constraints.append((parent_class, parent_class._meta.constraints))
         return constraints
@@ -1855,7 +1855,7 @@ class Model(AltersData, metaclass=ModelBase):
         used_fields = {}  # name or attname -> field
 
         # Check that multi-inheritance doesn't cause field name shadowing.
-        for parent in cls._meta.get_parent_list():
+        for parent in cls._meta.all_parents:
             for f in parent._meta.local_fields:
                 clash = used_fields.get(f.name) or used_fields.get(f.attname) or None
                 if clash:
@@ -1875,7 +1875,7 @@ class Model(AltersData, metaclass=ModelBase):
         # Check that fields defined in the model don't clash with fields from
         # parents, including auto-generated fields like multi-table inheritance
         # child accessors.
-        for parent in cls._meta.get_parent_list():
+        for parent in cls._meta.all_parents:
             for f in parent._meta.get_fields():
                 if f not in used_fields:
                     used_fields[f.name] = f
diff --git a/django/db/models/deletion.py b/django/db/models/deletion.py
index 022dec940b..fd3d290a96 100644
--- a/django/db/models/deletion.py
+++ b/django/db/models/deletion.py
@@ -305,13 +305,11 @@ class Collector:
         if not collect_related:
             return
 
-        if keep_parents:
-            parents = set(model._meta.get_parent_list())
         model_fast_deletes = defaultdict(list)
         protected_objects = defaultdict(list)
         for related in get_candidate_relations_to_delete(model._meta):
             # Preserve parent reverse relationships if keep_parents=True.
-            if keep_parents and related.model in parents:
+            if keep_parents and related.model in model._meta.all_parents:
                 continue
             field = related.field
             on_delete = field.remote_field.on_delete
diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index e59dfbe249..c7fe3b638a 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -1202,7 +1202,7 @@ class RawSQL(Expression):
     ):
         # Resolve parents fields used in raw SQL.
         if query.model:
-            for parent in query.model._meta.get_parent_list():
+            for parent in query.model._meta.all_parents:
                 for parent_field in parent._meta.local_fields:
                     if parent_field.column.lower() in self.sql.lower():
                         query.resolve_ref(
diff --git a/django/db/models/options.py b/django/db/models/options.py
index e63a81c2d8..7e2896a6a2 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -692,16 +692,24 @@ class Options:
                 return res
         return []
 
-    def get_parent_list(self):
+    @cached_property
+    def all_parents(self):
         """
-        Return all the ancestors of this model as a list ordered by MRO.
+        Return all the ancestors of this model as a tuple ordered by MRO.
         Useful for determining if something is an ancestor, regardless of lineage.
         """
         result = OrderedSet(self.parents)
         for parent in self.parents:
-            for ancestor in parent._meta.get_parent_list():
+            for ancestor in parent._meta.all_parents:
                 result.add(ancestor)
-        return list(result)
+        return tuple(result)
+
+    def get_parent_list(self):
+        """
+        Return all the ancestors of this model as a list ordered by MRO.
+        Backward compatibility method.
+        """
+        return list(self.all_parents)
 
     def get_ancestor_link(self, ancestor):
         """
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 94819758dd..cb5c63c0d1 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -788,7 +788,7 @@ class QuerySet(AltersData):
         # model to detect the inheritance pattern ConcreteGrandParent ->
         # MultiTableParent -> ProxyChild. Simply checking self.model._meta.proxy
         # would not identify that case as involving multiple tables.
-        for parent in self.model._meta.get_parent_list():
+        for parent in self.model._meta.all_parents:
             if parent._meta.concrete_model is not self.model._meta.concrete_model:
                 raise ValueError("Can't bulk create a multi-table inherited model")
         if not objs:
diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py
index e1041b9653..7162c4fea9 100644
--- a/django/db/models/query_utils.py
+++ b/django/db/models/query_utils.py
@@ -403,8 +403,8 @@ def check_rel_lookup_compatibility(model, target_opts, field):
     def check(opts):
         return (
             model._meta.concrete_model == opts.concrete_model
-            or opts.concrete_model in model._meta.get_parent_list()
-            or model in opts.get_parent_list()
+            or opts.concrete_model in model._meta.all_parents
+            or model in opts.all_parents
         )
 
     # If the field is a primary key, then doing a query against the field's
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 9a0d2eb4e7..b36125c762 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -1391,7 +1391,7 @@ class SQLCompiler:
         def _get_parent_klass_info(klass_info):
             concrete_model = klass_info["model"]._meta.concrete_model
             for parent_model, parent_link in concrete_model._meta.parents.items():
-                parent_list = parent_model._meta.get_parent_list()
+                all_parents = parent_model._meta.all_parents
                 yield {
                     "model": parent_model,
                     "field": parent_link,
@@ -1402,7 +1402,7 @@ class SQLCompiler:
                         # Selected columns from a model or its parents.
                         if (
                             self.select[select_index][0].target.model == parent_model
-                            or self.select[select_index][0].target.model in parent_list
+                            or self.select[select_index][0].target.model in all_parents
                         )
                     ],
                 }
diff --git a/django/forms/models.py b/django/forms/models.py
index 4b11d5af8c..4cda4e534e 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -1214,20 +1214,19 @@ def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
         fks_to_parent = [f for f in opts.fields if f.name == fk_name]
         if len(fks_to_parent) == 1:
             fk = fks_to_parent[0]
-            parent_list = parent_model._meta.get_parent_list()
-            parent_list.append(parent_model)
+            all_parents = (*parent_model._meta.all_parents, parent_model)
             if (
                 not isinstance(fk, ForeignKey)
                 or (
                     # ForeignKey to proxy models.
                     fk.remote_field.model._meta.proxy
-                    and fk.remote_field.model._meta.proxy_for_model not in parent_list
+                    and fk.remote_field.model._meta.proxy_for_model not in all_parents
                 )
                 or (
                     # ForeignKey to concrete models.
                     not fk.remote_field.model._meta.proxy
                     and fk.remote_field.model != parent_model
-                    and fk.remote_field.model not in parent_list
+                    and fk.remote_field.model not in all_parents
                 )
             ):
                 raise ValueError(
@@ -1240,18 +1239,17 @@ def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
             )
     else:
         # Try to discover what the ForeignKey from model to parent_model is
-        parent_list = parent_model._meta.get_parent_list()
-        parent_list.append(parent_model)
+        all_parents = (*parent_model._meta.all_parents, parent_model)
         fks_to_parent = [
             f
             for f in opts.fields
             if isinstance(f, ForeignKey)
             and (
                 f.remote_field.model == parent_model
-                or f.remote_field.model in parent_list
+                or f.remote_field.model in all_parents
                 or (
                     f.remote_field.model._meta.proxy
-                    and f.remote_field.model._meta.proxy_for_model in parent_list
+                    and f.remote_field.model._meta.proxy_for_model in all_parents
                 )
             )
         ]
diff --git a/tests/model_meta/tests.py b/tests/model_meta/tests.py
index fef82661cd..0aa04d760d 100644
--- a/tests/model_meta/tests.py
+++ b/tests/model_meta/tests.py
@@ -325,15 +325,19 @@ class RelationTreeTests(SimpleTestCase):
         )
 
 
-class ParentListTests(SimpleTestCase):
-    def test_get_parent_list(self):
-        self.assertEqual(CommonAncestor._meta.get_parent_list(), [])
-        self.assertEqual(FirstParent._meta.get_parent_list(), [CommonAncestor])
-        self.assertEqual(SecondParent._meta.get_parent_list(), [CommonAncestor])
+class AllParentsTests(SimpleTestCase):
+    def test_all_parents(self):
+        self.assertEqual(CommonAncestor._meta.all_parents, ())
+        self.assertEqual(FirstParent._meta.all_parents, (CommonAncestor,))
+        self.assertEqual(SecondParent._meta.all_parents, (CommonAncestor,))
         self.assertEqual(
-            Child._meta.get_parent_list(), [FirstParent, SecondParent, CommonAncestor]
+            Child._meta.all_parents,
+            (FirstParent, SecondParent, CommonAncestor),
         )
 
+    def test_get_parent_list(self):
+        self.assertEqual(Child._meta.get_parent_list(), list(Child._meta.all_parents))
+
 
 class PropertyNamesTests(SimpleTestCase):
     def test_person(self):