950         if constant.type in ('Date', 'Datetime'):

   950         if constant.type in ('Date', 'Datetime'):

   951             rel = constant.relation()

   951             rel = constant.relation()

   952             if rel is not None:

   952             if rel is not None:

   953                 rel._q_needcast = value

   953                 rel._q_needcast = value

   954             return self.keyword_map[value]()

   954             return self.keyword_map[value]()

   955         if constant.type == 'Substitute':

   957         if constant.type == 'Substitute':

   956             _id = constant.value

   958             _id = constant.value

   957             if isinstance(_id, unicode):

   959             if isinstance(_id, unicode):

   958                 _id = _id.encode()

   960                 _id = _id.encode()

   959         else:

   961         else: