Alchemy object json Encoder

AlchemyEncoder.py

import json
from datetime import datetime
from sqlalchemy.ext.declarative import DeclarativeMeta


class AlchemyEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj.__class__, DeclarativeMeta):
            # an SQLAlchemy class
            fields = {}
            for field in [c.key for c in inspect(obj).mapper.column_attrs]:
                data = obj.__getattribute__(field)
                try:
                    if isinstance(data, datetime):
                        data = data.strftime('%Y-%m-%d %H:%M:%S')
                    json.dumps(data)  # this will fail on non-encodable values, like other classes
                    fields[field] = data
                except TypeError:
                    fields[field] = None
            # a json-encodable dict
            return fields

        return json.JSONEncoder.default(self, obj)