Added more human-readable error message for invalid frames for range/…

…span (arrow-py#407) * Added more human-readable error message for invalid frames for range/span * Fixed empty field name for string interpolation in range/span error message
it-ailen · Jan 24, 2017 · a78bb2f · a78bb2f
1 parent 93f4890
commit a78bb2f
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/arrow/arrow.py b/arrow/arrow.py
@@ -1020,7 +1020,8 @@ def _get_frames(cls, name):
         elif name in ['quarter', 'quarters']:
             return 'quarter', 'months', 3
 
-        raise AttributeError()
+        supported = ', '.join(cls._ATTRS + ['week', 'weeks'] + ['quarter', 'quarters'])
+        raise AttributeError('range/span over frame {0} not supported. Supported frames: {1}'.format(name, supported))
 
     @classmethod
     def _get_iteration_params(cls, end, limit):