class AlchemyEncoder(json.JSONEncoder):

    def default(self, obj):
        if isinstance(obj.__class__, DeclarativeMeta):
            if obj in _visited_objs:
                return None
_visited_objs.append(obj)
fields = {}
for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata'
    ]:
    fields[field] = obj.__getattribute__(field)
return fields
return json.JSONEncoder.default(self, obj)
return AlchemyEncoder
How to serialize SqlAlchemy result to JSON?