Значение по умолчанию для ndb.KeyProperty

Question

У меня есть эти две модели:

################# 
### Usergroup ### 
################# 

class Usergroup(ndb.Model): 
    group_name = ndb.StringProperty(indexed = False, required = True) 
    is_admin_group = ndb.BooleanProperty(indexed = False, required = False, default = False) 

############ 
### User ### 
############ 

class User(ndb.Model): 
    fb_id = ndb.StringProperty(indexed = True, required = True) 
    fb_access_token = ndb.TextProperty(indexed = False, required = True) 
    email = ndb.StringProperty(indexed = True, required = True) 
    first_name = ndb.StringProperty(indexed = False, required = True) 
    last_name = ndb.StringProperty(indexed = False, required = True) 
    gender = ndb.StringProperty(indexed = False) 
    group_key = ndb.KeyProperty(indexed = False, required = False, kind = Usergroup, default = ndb.Key(Usergroup, 'member')) 
    join_date = ndb.DateTimeProperty(indexed = True, auto_now_add = True) 
    last_login = ndb.DateTimeProperty(indexed = True, auto_now_add = True, auto_now = False) 

@app.route('/user/login', methods=['POST']) 
def user_login(): 
    me = exchange_token_me(request.form['accessToken']) 
    if me is not False: 
     user = user_find_or_register(me) 
     if user is not None: 
      register_session(user) 
      return 'success' 
    return 'error' 

def user_find_or_register(user): 
    qry = User.query(User.fb_id == user['id']) 
    existing_user = qry.get() 

    if existing_user is not None: 
     existing_user.fb_access_token = user['access_token'] 
     existing_user.fb_id = user['id'] 
     existing_user.email = user['email'] 
     existing_user.last_login = datetime.datetime.now() 
     existing_user.put() 
     return existing_user 

    new_user = User() 
    new_user.fb_id = user['id'] 
    new_user.fb_access_token = user['access_token'] 
    new_user.email = user['email'] 
    new_user.first_name = user['first_name'] 
    new_user.last_name = user['last_name'] 
    new_user.gender = user['gender'] 
    new_user.last_login = datetime.datetime.now() 
    #new_user.group_key = ndb.key(Usergroup, 'member') 

    key = new_user.put() 
    saved_user = key.get() 
    #key.delete() # DEBUG 

    if saved_user is not None: 
     return saved_user 

def register_session(user): 
    session['fb_id'] = user.fb_id 
    session['first_name'] = user.first_name 
    session['last_name'] = user.last_name 
    session['group_key'] = user.group_key 
    session['loggedin'] = True 

Модель UserGroup имеет небольшую уникальную строку ключа сущности. Существует уже UserGroup, чей ключ «член»

Всякий раз, когда мы создаем/сохранения пользователя, он должен использовать ключ к группе пользователей «членов», но мы получаем эту ошибку вместо того, чтобы:

TypeError: Ключ ('UserGroup', 'член') не является JSON-сериализации

Traceback:

ERROR 2016-10-18 14:32:40,572 app.py:1587] Exception on /user/login [POST] 
Traceback (most recent call last): 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1988, in wsgi_app 
    response = self.full_dispatch_request() 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1643, in full_dispatch_request 
    response = self.process_response(response) 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1864, in process_response 
    self.save_session(ctx.session, response) 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 926, in save_session 
    return self.session_interface.save_session(self, session, response) 
    File "/var/www/mywebsite/public_html/lib/flask/sessions.py", line 359, in save_session 
    val = self.get_signing_serializer(app).dumps(dict(session)) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 565, in dumps 
    payload = want_bytes(self.dump_payload(obj)) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 847, in dump_payload 
    json = super(URLSafeSerializerMixin, self).dump_payload(obj) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 550, in dump_payload 
    return want_bytes(self.serializer.dumps(obj)) 
    File "/var/www/mywebsite/public_html/lib/flask/sessions.py", line 85, in dumps 
    return json.dumps(_tag(value), separators=(',', ':')) 
    File "/var/www/mywebsite/public_html/lib/flask/json.py", line 126, in dumps 
    rv = _json.dumps(obj, **kwargs) 
    File "/usr/lib/python2.7/json/__init__.py", line 251, in dumps 
    sort_keys=sort_keys, **kw).encode(obj) 
    File "/usr/lib/python2.7/json/encoder.py", line 209, in encode 
    chunks = list(chunks) 
    File "/usr/lib/python2.7/json/encoder.py", line 434, in _iterencode 
    for chunk in _iterencode_dict(o, _current_indent_level): 
    File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict 
    for chunk in chunks: 
    File "/usr/lib/python2.7/json/encoder.py", line 442, in _iterencode 
    o = _default(o) 
    File "/var/www/mywebsite/public_html/lib/flask/json.py", line 83, in default 
    return _json.JSONEncoder.default(self, o) 
    File "/usr/lib/python2.7/json/encoder.py", line 184, in default 
    raise TypeError(repr(o) + " is not JSON serializable") 
TypeError: Key('Usergroup', 'member') is not JSON serializable 
ERROR 2016-10-18 14:32:40,593 main.py:178] An error occurred during a request. 
Traceback (most recent call last): 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1988, in wsgi_app 
    response = self.full_dispatch_request() 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1643, in full_dispatch_request 
    response = self.process_response(response) 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 1864, in process_response 
    self.save_session(ctx.session, response) 
    File "/var/www/mywebsite/public_html/lib/flask/app.py", line 926, in save_session 
    return self.session_interface.save_session(self, session, response) 
    File "/var/www/mywebsite/public_html/lib/flask/sessions.py", line 359, in save_session 
    val = self.get_signing_serializer(app).dumps(dict(session)) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 565, in dumps 
    payload = want_bytes(self.dump_payload(obj)) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 847, in dump_payload 
    json = super(URLSafeSerializerMixin, self).dump_payload(obj) 
    File "/var/www/mywebsite/public_html/lib/itsdangerous.py", line 550, in dump_payload 
    return want_bytes(self.serializer.dumps(obj)) 
    File "/var/www/mywebsite/public_html/lib/flask/sessions.py", line 85, in dumps 
    return json.dumps(_tag(value), separators=(',', ':')) 
    File "/var/www/mywebsite/public_html/lib/flask/json.py", line 126, in dumps 
    rv = _json.dumps(obj, **kwargs) 
    File "/usr/lib/python2.7/json/__init__.py", line 251, in dumps 
    sort_keys=sort_keys, **kw).encode(obj) 
    File "/usr/lib/python2.7/json/encoder.py", line 209, in encode 
    chunks = list(chunks) 
    File "/usr/lib/python2.7/json/encoder.py", line 434, in _iterencode 
    for chunk in _iterencode_dict(o, _current_indent_level): 
    File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict 
    for chunk in chunks: 
    File "/usr/lib/python2.7/json/encoder.py", line 442, in _iterencode 
    o = _default(o) 
    File "/var/www/mywebsite/public_html/lib/flask/json.py", line 83, in default 
    return _json.JSONEncoder.default(self, o) 
    File "/usr/lib/python2.7/json/encoder.py", line 184, in default 
    raise TypeError(repr(o) + " is not JSON serializable") 
TypeError: Key('Usergroup', 'member') is not JSON serializable 
INFO  2016-10-18 14:32:40,610 module.py:788] default: "POST /user/login HTTP/1.1" 500 27 

ОБНОВЛЕНИЕ: После того, как Дэн заметил проблему, решение в следующей функции:

def register_session(user): 
    session['fb_id'] = user.fb_id 
    session['first_name'] = user.first_name 
    session['last_name'] = user.last_name 
    session['group_key'] = user.group_key.id() # Thanks Dan 
    session['loggedin'] = True 

Answer 1

FWIW, быстрый тест с кодом, как models.py показывает, что это будет работать нормально, по крайней мере, на сервере разработки:

from models import User 

    user = User(email='email', username='username') 
    user.put() 

производства:

Это работало даже без наличия объекта Usergroup - ключ может существовать без соответствующего объекта. Конечно, пытаясь следовать по ссылке на UserGroup в зрителе датастора терпит неудачу:

Traceback (most recent call last): 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 1536, in __call__ 
    rv = self.handle_exception(request, response, e) 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 1530, in __call__ 
    rv = self.router.dispatch(request, response) 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 1278, in default_dispatcher 
    return route.handler_adapter(request, response) 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 1102, in __call__ 
    return handler.dispatch() 
    File "/home/usr_local/google_appengine/google/appengine/tools/devappserver2/admin/admin_request_handler.py", line 96, in dispatch 
    super(AdminRequestHandler, self).dispatch() 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 572, in dispatch 
    return self.handle_exception(e, self.app.debug) 
    File "/home/usr_local/google_appengine_1.9.40/lib/webapp2-2.5.1/webapp2.py", line 570, in dispatch 
    return method(*args, **kwargs) 
    File "/home/usr_local/google_appengine/google/appengine/tools/devappserver2/admin/datastore_viewer.py", line 741, in get 
    entities = [datastore.Get(entity_key)] 
    File "/home/usr_local/google_appengine/google/appengine/api/datastore.py", line 671, in Get 
    return GetAsync(keys, **kwargs).get_result() 
    File "/home/usr_local/google_appengine/google/appengine/api/apiproxy_stub_map.py", line 613, in get_result 
    return self.__get_result_hook(self) 
    File "/home/usr_local/google_appengine/google/appengine/datastore/datastore_rpc.py", line 1717, in __get_hook 
    entities = extra_hook(entities) 
    File "/home/usr_local/google_appengine/google/appengine/api/datastore.py", line 640, in local_extra_hook 
    raise datastore_errors.EntityNotFoundError() 
EntityNotFoundError 

Таким образом, вы можете показать ваш фактический код создает объект и полное отслеживающий, что-то еще может идти.

Ваш отслеживающий указывает, что проблема не с созданием объект, но с сохранением сеанса:

File "/var/www/mywebsite/public_html/lib/flask/app.py", line 926, in save_session 
    return self.session_interface.save_session(self, session, response) 

Похоже, вы включены в содержание сеанса ключевой объект (возможно, в том числе весь User объект?), что и является причиной сбоя. Для этого ключи должны быть сериализованы, и для этого вы можете использовать key.urlsafe(). См. Этот ответ для примера: https://stackoverflow.com/a/34835074/4495081

Если вы включили в сеанс весь объект User, вы можете просто включить его ключ urlsafe.

Да, это источник вашей проблемы:

session['group_key'] = user.group_key 

изменить его:

session['group_key'] = user.group_key.urlsafe() 

И вы будете получать это так:

urlsafe_key = session.get('group_key') 
if urlsafe_key: 
    group_key = ndb.Key(urlsafe=urlsafe_key)