diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index 75d429eb4..a3f7fdcc1 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -1157,6 +1157,9 @@ The [html-json-forms][html-json-forms] package provides an algorithm and seriali
 
 [djangorestframework-queryfields][djangorestframework-queryfields] allows API clients to specify which fields will be sent in the response via inclusion/exclusion query parameters.  
 
+## DRF Writable Nested
+
+The [drf-writable-nested][drf-writable-nested] package provides writable nested model serializer which allows to create/update models with nested related data.
 
 [cite]: https://groups.google.com/d/topic/django-users/sVFaOfQi4wY/discussion
 [relations]: relations.md
@@ -1177,3 +1180,4 @@ The [html-json-forms][html-json-forms] package provides an algorithm and seriali
 [drf-base64]: https://bitbucket.org/levit_scs/drf_base64
 [drf-serializer-extensions]: https://github.com/evenicoulddoit/django-rest-framework-serializer-extensions
 [djangorestframework-queryfields]: http://djangorestframework-queryfields.readthedocs.io/
+[drf-writable-nested]: http://github.com/Brogency/drf-writable-nested
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index f46edef1e..2efe89610 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1446,11 +1446,11 @@ class FileField(Field):
         return data
 
     def to_representation(self, value):
-        use_url = getattr(self, 'use_url', api_settings.UPLOADED_FILES_USE_URL)
-
         if not value:
             return None
 
+        use_url = getattr(self, 'use_url', api_settings.UPLOADED_FILES_USE_URL)
+
         if use_url:
             if not getattr(value, 'url', None):
                 # If the file has not been saved it may not have a URL.
diff --git a/rest_framework/request.py b/rest_framework/request.py
index b4bd2d020..9428708ed 100644
--- a/rest_framework/request.py
+++ b/rest_framework/request.py
@@ -353,10 +353,9 @@ class Request(object):
 
     def _not_authenticated(self):
         """
-        Return a three-tuple of (authenticator, user, authtoken), representing
-        an unauthenticated request.
+        Set authenticator, user & authtoken representing an unauthenticated request.
 
-        By default this will be (None, AnonymousUser, None).
+        Defaults are None, AnonymousUser & None.
         """
         self._authenticator = None