Error with Proxy() when remote reference returns empty result set

[Nick Snell]

With storm 0.18 when using Proxy() to a Reference field, when the Reference is None the attribue access to the Proxy falls over with a seemingly random error message:

   AttributeError: "'NoneType' object has no attribute '__dict__'"

   function __get__ in references.py at line 417
       return self._remote_prop.__get__(self._reference.__get__(obj))
   function __get__ in properties.py at line 53
       return self._get_column(cls)
   function _get_column in properties.py at line 92
       column = cls.__dict__["_storm_columns"].get(self)

attached is a working example of the bug.

I don't know enough about it to submit a patch, however I believe in the __get__ in Proxy it should be first checking if the the reference object can be retrieved before proceeding. Adding this resolved the issue:

   if self._reference.__get__(obj) == None:
               return None

before the return:

   return self._remote_prop.__get__(self._reference.__get__(obj))

If I can provide anymore info please let me know.

Nick