Add test and fix for #2704

rest_framework/serializers.py

@@ -13,7 +13,6 @@ response content is handled by parsers and renderers.
 from __future__ import unicode_literals
 from django.db import models
 from django.db.models.fields import FieldDoesNotExist, Field as DjangoModelField
-from django.db.models import query
 from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 from rest_framework.compat import (
@@ -579,7 +578,8 @@ class ListSerializer(BaseSerializer):
         """
         # Dealing with nested relationships, data can be a Manager,
         # so, first get a queryset from the Manager if needed
-        iterable = data.all() if isinstance(data, (models.Manager, query.QuerySet)) else data
+        iterable = data.all() if isinstance(data, models.Manager) else data
+
         return [
             self.child.to_representation(item) for item in iterable
         ]

tests/test_model_serializer.py

@@ -721,3 +721,28 @@ class TestSerializerMetaClass(TestCase):
             str(exception),
             "Cannot set both 'fields' and 'exclude' options on serializer ExampleSerializer."
         )
+
+
+class Issue2704TestCase(TestCase):
+    def test_queryset_all(self):
+        class TestSerializer(serializers.ModelSerializer):
+            additional_attr = serializers.CharField()
+
+            class Meta:
+                model = OneFieldModel
+                fields = ('char_field', 'additional_attr')
+
+        OneFieldModel.objects.create(char_field='abc')
+        qs = OneFieldModel.objects.all()
+
+        for o in qs:
+            o.additional_attr = '123'
+
+        serializer = TestSerializer(instance=qs, many=True)
+
+        expected = [{
+            'char_field': 'abc',
+            'additional_attr': '123',
+        }]
+
+        assert serializer.data == expected