From a084c5d35a6d00abd261338a374a4424764b4aee Mon Sep 17 00:00:00 2001
From: AlexCLeduc <ledualex@gmail.com>
Date: Mon, 19 Feb 2024 17:36:04 -0500
Subject: [PATCH] Fixed #35238 -- Fixed database serialization crash when base
 managers use prefetch_related().

Regression in 139135627650ed6aaaf4c755b82c3bd43f2b8f51
following deprecation in eedbf930287cb72e9afab1f7208c24b1146b0c4ec.
---
 django/db/backends/base/creation.py  |  5 ++++-
 docs/releases/5.0.3.txt              |  4 ++++
 tests/backends/base/test_creation.py | 17 +++++++++++++++++
 tests/backends/models.py             | 14 ++++++++++++++
 4 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/django/db/backends/base/creation.py b/django/db/backends/base/creation.py
index cbac8a7f7672..6856fdb59676 100644
--- a/django/db/backends/base/creation.py
+++ b/django/db/backends/base/creation.py
@@ -135,7 +135,10 @@ def get_objects():
                             queryset = model._base_manager.using(
                                 self.connection.alias,
                             ).order_by(model._meta.pk.name)
-                            yield from queryset.iterator()
+                            chunk_size = (
+                                2000 if queryset._prefetch_related_lookups else None
+                            )
+                            yield from queryset.iterator(chunk_size=chunk_size)
 
         # Serialize to a string
         out = StringIO()
diff --git a/docs/releases/5.0.3.txt b/docs/releases/5.0.3.txt
index e17fdd531f13..297e17d02359 100644
--- a/docs/releases/5.0.3.txt
+++ b/docs/releases/5.0.3.txt
@@ -24,3 +24,7 @@ Bugfixes
 * Fixed a regression in Django 5.0 that caused a crash of
   ``@sensitive_variables`` and ``@sensitive_post_parameters`` decorators on
   functions loaded from ``.pyc`` files (:ticket:`35187`).
+
+* Fixed a regression in Django 5.0 that caused a crash when reloading a test
+  database and a base queryset for a base manager used ``prefetch_related()``
+  (:ticket:`35238`).
diff --git a/tests/backends/base/test_creation.py b/tests/backends/base/test_creation.py
index 9593e13462a0..7e760e88845a 100644
--- a/tests/backends/base/test_creation.py
+++ b/tests/backends/base/test_creation.py
@@ -14,6 +14,7 @@
     Object,
     ObjectReference,
     ObjectSelfReference,
+    SchoolBus,
     SchoolClass,
 )
 
@@ -250,6 +251,22 @@ def test_serialize_db_to_string_base_manager(self):
         self.assertIn('"model": "backends.schoolclass"', data)
         self.assertIn('"year": 1000', data)
 
+    def test_serialize_db_to_string_base_manager_with_prefetch_related(self):
+        sclass = SchoolClass.objects.create(
+            year=2000, last_updated=datetime.datetime.now()
+        )
+        bus = SchoolBus.objects.create(number=1)
+        bus.schoolclasses.add(sclass)
+        with mock.patch("django.db.migrations.loader.MigrationLoader") as loader:
+            # serialize_db_to_string() serializes only migrated apps, so mark
+            # the backends app as migrated.
+            loader_instance = loader.return_value
+            loader_instance.migrated_apps = {"backends"}
+            data = connection.creation.serialize_db_to_string()
+        self.assertIn('"model": "backends.schoolbus"', data)
+        self.assertIn('"model": "backends.schoolclass"', data)
+        self.assertIn(f'"schoolclasses": [{sclass.pk}]', data)
+
 
 class SkipTestClass:
     def skip_function(self):
diff --git a/tests/backends/models.py b/tests/backends/models.py
index 99e9e86f44d2..1ed108c2b8c7 100644
--- a/tests/backends/models.py
+++ b/tests/backends/models.py
@@ -32,6 +32,20 @@ class SchoolClass(models.Model):
     objects = SchoolClassManager()
 
 
+class SchoolBusManager(models.Manager):
+    def get_queryset(self):
+        return super().get_queryset().prefetch_related("schoolclasses")
+
+
+class SchoolBus(models.Model):
+    number = models.IntegerField()
+    schoolclasses = models.ManyToManyField("SchoolClass")
+    objects = SchoolBusManager()
+
+    class Meta:
+        base_manager_name = "objects"
+
+
 class VeryLongModelNameZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ(models.Model):
     primary_key_is_quite_long_zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz = models.AutoField(
         primary_key=True