import requests
from json_serde import JsonSerde, Integer, String, IsoDateTime


class User(JsonSerde):
    username = String()
    user_id = Integer(rename='userId')
    birthday = IsoDateTime(is_optional=True, default=None)


resp = requests.get('https://example.com/api/user')
resp.raise_for_status()

api_response = resp.json()
# {'username': 'emmag', 'userId': 1312, 'somethingElse': ['irrelevant']}

user = User.from_json(api_response)
assert user.username == 'emmag'
assert isinstance(user.user_id, int)
assert user.birthday is None