Python 访问令牌无效时的Google日历API

我正在尝试在谷歌日历中获取特定日期范围内的事件。我正在做以下工作：

    credentials = AccessTokenCredentials.from_json(token_json)
    http = httplib2.Http()
    if credentials.access_token_expired:
        credentials.refresh(http)
    else:
        http = credentials.authorize(http)

    service = build(serviceName='calendar', version='v3', http=http)
    events = service.events().list(calendarId='primary', pageToken=None,
                                   timeMin=rfc3339(start_dt),
                                   timeMax=rfc3339(end_dt))
    events = events.execute()

由于某种原因，当我到达最后一行时，我得到以下错误：

AccessTokenCredentialsError: The access_token is expired or invalid and can't be refreshed.

当我使用断点时，它在if语句中从不说

access\u token\u expired

。这个用例怎么总是失败？我在刷新代币方面有什么地方做错了吗

关于这一点，我阅读了以下内容：

---

尝试测试

凭据。无效的

我有一个小程序，用来确保存储的凭证对于gmail单元测试总是新鲜的。它可能/可能不适合你的情况

from oauth2client.client import OAuth2WebServerFlow
from oauth2client.client import flow_from_clientsecrets
from oauth2client.file import Storage
from oauth2client import tools

# the stored credentials file to use for these tests
TEST_CREDENTIALS_FILE = 'testjoe.storage'


def get_credentials():
    """Utility routine to returns credentials for testing use"""

    # Location of the credentials storage file
    storage = Storage(TEST_CREDENTIALS_FILE)

    # Start the OAuth flow to retrieve credentials
    flow = flow_from_clientsecrets('client_secret_native.json', scope='https://www.googleapis.com/auth/gmail.modify')

    # Try to retrieve credentials from storage or run the flow to generate them
    credentials = storage.get()
    if credentials is None or credentials.invalid:
        flags = tools.argparser.parse_args(args=[])
        credentials = tools.run_flow(flow, storage, flags)
    return credentials

你是怎么修好的？我正在使用相同的方法，无法刷新令牌。。。我将非常感谢任何指导。我正在将AccessTokenCredentials与已获得的令牌（手动用户同意）一起使用。我有两个令牌，但我无法刷新令牌！我的问题是我没有正确存储令牌的数据。我将
凭据保存到我的数据库中。to_json（）
。您能修复它吗？如果“是”，那么怎么做？