From 981a072dd4dec586f8fc606712ed9a2ef116eeee Mon Sep 17 00:00:00 2001
From: Kwist <velnik@gmail.com>
Date: Mon, 31 Aug 2020 11:54:34 +0300
Subject: [PATCH] Fixed #31843 -- Fixed pickling named values from
 QuerySet.values_list().

---
 AUTHORS                   |  1 +
 django/db/models/query.py | 13 ++-----------
 django/db/models/utils.py | 18 ++++++++++++++++++
 tests/queries/tests.py    |  5 +++++
 4 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index 7e316cd739..81858e7b29 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -934,6 +934,7 @@ answer newbie questions, and generally made Django that much better:
     Vincent Foley <vfoleybourgon@yahoo.ca>
     Vinny Do <vdo.code@gmail.com>
     Vitaly Babiy <vbabiy86@gmail.com>
+    Vitaliy Yelnik <velnik@gmail.com>
     Vladimir Kuzma <vladimirkuzma.ch@gmail.com>
     Vlado <vlado@labath.org>
     Vsevolod Solovyov
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 67ffe7f000..6c78fbc4b3 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -5,8 +5,6 @@ The main QuerySet implementation. This provides the public API for the ORM.
 import copy
 import operator
 import warnings
-from collections import namedtuple
-from functools import lru_cache
 from itertools import chain
 
 import django
@@ -23,7 +21,7 @@ from django.db.models.expressions import Case, Expression, F, Value, When
 from django.db.models.functions import Cast, Trunc
 from django.db.models.query_utils import FilteredRelation, Q
 from django.db.models.sql.constants import CURSOR, GET_ITERATOR_CHUNK_SIZE
-from django.db.models.utils import resolve_callables
+from django.db.models.utils import create_namedtuple_class, resolve_callables
 from django.utils import timezone
 from django.utils.functional import cached_property, partition
 
@@ -148,13 +146,6 @@ class NamedValuesListIterable(ValuesListIterable):
     namedtuple for each row.
     """
 
-    @staticmethod
-    @lru_cache()
-    def create_namedtuple_class(*names):
-        # Cache namedtuple() with @lru_cache() since it's too slow to be
-        # called for every QuerySet evaluation.
-        return namedtuple('Row', names)
-
     def __iter__(self):
         queryset = self.queryset
         if queryset._fields:
@@ -162,7 +153,7 @@ class NamedValuesListIterable(ValuesListIterable):
         else:
             query = queryset.query
             names = [*query.extra_select, *query.values_select, *query.annotation_select]
-        tuple_class = self.create_namedtuple_class(*names)
+        tuple_class = create_namedtuple_class(*names)
         new = tuple.__new__
         for row in super().__iter__():
             yield new(tuple_class, row)
diff --git a/django/db/models/utils.py b/django/db/models/utils.py
index 989667dc8c..764ca5888b 100644
--- a/django/db/models/utils.py
+++ b/django/db/models/utils.py
@@ -1,3 +1,7 @@
+import functools
+from collections import namedtuple
+
+
 def make_model_tuple(model):
     """
     Take a model or a string of the form "app_label.ModelName" and return a
@@ -28,3 +32,17 @@ def resolve_callables(mapping):
     """
     for k, v in mapping.items():
         yield k, v() if callable(v) else v
+
+
+def unpickle_named_row(names, values):
+    return create_namedtuple_class(*names)(*values)
+
+
+@functools.lru_cache()
+def create_namedtuple_class(*names):
+    # Cache type() with @lru_cache() since it's too slow to be called for every
+    # QuerySet evaluation.
+    def __reduce__(self):
+        return unpickle_named_row, (names, tuple(self))
+
+    return type('Row', (namedtuple('Row', names),), {'__reduce__': __reduce__})
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index 428153402f..5b667186a3 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -2408,6 +2408,11 @@ class ValuesQuerysetTests(TestCase):
         values = qs.first()
         self.assertEqual(values._fields, ('combinedexpression2', 'combinedexpression1'))
 
+    def test_named_values_pickle(self):
+        value = Number.objects.values_list('num', 'other_num', named=True).get()
+        self.assertEqual(value, (72, None))
+        self.assertEqual(pickle.loads(pickle.dumps(value)), value)
+
 
 class QuerySetSupportsPythonIdioms(TestCase):