Merge pull request #230 from macisamuele/maci-ensure-that-renderer-us…

…es-operation-as-optional

Gracefully handle operation attribute not set in request during rendering

pyramid_swagger/renderer.py

@@ -17,7 +17,7 @@ def __init__(self, renderer_factory=JSON()):
 
     def _marshal_object(self, request, response_object):
         # operation attribute is injected by validator_tween in case the endpoint is served by Swagger 2.0 specs
-        operation = getattr(request, 'operation')
+        operation = getattr(request, 'operation', None)
 
         if not operation:
             # If the request is not served by Swagger2.0 endpoint _marshal_object is NO_OP