import datetime
import json


class Serializer:
    serializable_fields = []

    def get_serializable_fields(self):
        return self.serializable_fields

    def get_data(self):
        data = {}

        for field in self.get_serializable_fields():
            if hasattr(self, field):
                if isinstance(getattr(self, field), datetime.date):
                    data.update({field: getattr(self, field).isoformat()})
                else:
                    data.update({field: getattr(self, field)})
            else:
                raise AttributeError(
                    "This object does not have a field named '{}'".format(field)
                )

        return data

    def to_json(self):
        return json.dumps(self.get_data())