set Retry-After header when throttled

rest_framework/exceptions.py

@@ -71,7 +71,7 @@ class UnsupportedMediaType(APIException):
 class Throttled(APIException):
     status_code = status.HTTP_429_TOO_MANY_REQUESTS
     default_detail = 'Request was throttled.'
-    extra_detail = "Expected available in %d second%s."
+    extra_detail = " Expected available in %d second%s."
 
     def __init__(self, wait=None, detail=None):
         if wait is None:

rest_framework/tests/test_throttling.py

@@ -117,8 +117,10 @@ class ThrottlingTests(TestCase):
             response = view.as_view()(request)
             if expect is not None:
                 self.assertEqual(response['X-Throttle-Wait-Seconds'], expect)
+                self.assertEqual(response['Retry-After'], expect)
             else:
                 self.assertFalse('X-Throttle-Wait-Seconds' in response)
+                self.assertFalse('Retry-After' in response)
 
     def test_seconds_fields(self):
         """
@@ -165,11 +167,13 @@ class ThrottlingTests(TestCase):
 
         response = MockView_NonTimeThrottling.as_view()(request)
         self.assertFalse('X-Throttle-Wait-Seconds' in response)
+        self.assertFalse('Retry-After' in response)
 
         self.assertTrue(MockView_NonTimeThrottling.throttle_classes[0].called)
 
         response = MockView_NonTimeThrottling.as_view()(request)
         self.assertFalse('X-Throttle-Wait-Seconds' in response) 
+        self.assertFalse('Retry-After' in response)
 
 
 class ScopedRateThrottleTests(TestCase):

rest_framework/views.py

@@ -61,6 +61,7 @@ def exception_handler(exc):
             headers['WWW-Authenticate'] = exc.auth_header
         if getattr(exc, 'wait', None):
             headers['X-Throttle-Wait-Seconds'] = '%d' % exc.wait
+            headers['Retry-After'] = '%d' % exc.wait
 
         return Response({'detail': exc.detail},
                         status=exc.status_code,