Refs #31051 -- Optimized serialize_db_to_string() by avoiding creation of models list.

django/db/backends/base/creation.py

@@ -97,24 +97,24 @@ class BaseDatabaseCreation:
         Designed only for test runner usage; will not handle large
         amounts of data.
         """
-        # Build list of all models to serialize.
+        # Iteratively return every object for all models to serialize.
+        def get_objects():
             from django.db.migrations.loader import MigrationLoader
             loader = MigrationLoader(self.connection)
-        model_list = []
             for app_config in apps.get_app_configs():
                 if (
                     app_config.models_module is not None and
                     app_config.label in loader.migrated_apps and
                     app_config.name not in settings.TEST_NON_SERIALIZED_APPS
                 ):
-                model_list.extend(app_config.get_models())
+                    for model in app_config.get_models():
-
+                        if (
-        # Make a function to iteratively return every object
+                            model._meta.can_migrate(self.connection) and
-        def get_objects():
+                            router.allow_migrate_model(self.connection.alias, model)
-            for model in model_list:
+                        ):
-                if (model._meta.can_migrate(self.connection) and
+                            queryset = model._default_manager.using(
-                        router.allow_migrate_model(self.connection.alias, model)):
+                                self.connection.alias,
-                    queryset = model._default_manager.using(self.connection.alias).order_by(model._meta.pk.name)
+                            ).order_by(model._meta.pk.name)
                             yield from queryset.iterator()
         # Serialize to a string
         out = StringIO()