如何在GAE任务队列中执行OAuthRequired操作？

Question

我有一个简单的googleappengine应用程序，其中包含一个更新YouTube播放列表的/update页面。看起来像这样：

class UpdatePage(webapp2.RequestHandler):

    @decorator.oauth_required
    def get(self):
        update_result = self.update_playlist()
        ...

routes = [('/update', UpdatePage),
          (decorator.callback_path, decorator.callback_handler())]
app = webapp2.WSGIApplication(routes, debug=True)

它按预期工作，update_playlist()方法完成了它的工作，但是在某些情况下，它可以运行很长时间，从而产生一个DeadlineExceededError。因此，在阅读了可用的选项之后，我认为任务队列API才是最好的选择（对吗？）我正在尝试使用它，遵循Using Push Queues in Python指南。在

简而言之，我把UpdatePage分成UpdatePageHandler+UpdatePageWorker：

^{pr2}$

不幸的是，在完成分割之后，我的OAuth2装饰器似乎不再执行它的工作：

INFO     2013-05-30 17:08:53,971 discovery.py:709] URL being requested: https://www.googleapis.com/youtube/v3/playlists?alt=json&part=snippet%2Cstatus
WARNING  2013-05-30 17:08:53,975 urlfetch_stub.py:480] Stripped prohibited headers from URLFetch request: ['content-length']
INFO     2013-05-30 17:08:54,351 client.py:493] Refreshing due to a 401
INFO     2013-05-30 17:08:54,361 appengine.py:276] make: Got type <class 'google.appengine.api.datastore_types.Blob'>
INFO     2013-05-30 17:08:54,363 appengine.py:289] validate: Got type <class 'oauth2client.client.OAuth2Credentials'>
INFO     2013-05-30 17:08:54,364 client.py:680] Refreshing access_token
INFO     2013-05-30 17:08:54,746 client.py:699] Failed to retrieve access token: {
  "error" : "invalid_grant"
}
INFO     2013-05-30 17:08:54,757 appengine.py:276] make: Got type <class 'google.appengine.api.datastore_types.Blob'>
INFO     2013-05-30 17:08:54,759 appengine.py:289] validate: Got type <class 'oauth2client.client.OAuth2Credentials'>
INFO     2013-05-30 17:08:54,761 appengine.py:289] validate: Got type <class 'oauth2client.client.OAuth2Credentials'>
INFO     2013-05-30 17:08:54,762 appengine.py:265] get: Got type <class 'oauth2client.appengine.CredentialsModel'>

如果不是装饰UpdateHandlerPage:get我装饰UpdateWorkerPage:post，我得到的是一个无限的失败循环：

INFO     2013-05-30 17:24:31,307 discovery.py:190] URL being requested: https://www.googleapis.com/discovery/v1/apis/youtube/v3/rest?userIp=127.0.0.1
INFO     2013-05-30 17:24:34,960 dev_appserver.py:3105] "GET /update HTTP/1.1" 200 -
INFO     2013-05-30 17:24:35,060 dev_appserver.py:3105] "POST /updateworker HTTP/1.1" 302 -
WARNING  2013-05-30 17:24:35,065 taskqueue_stub.py:1980] Task task1 failed to execute. This task will retry in 0.100 seconds
INFO     2013-05-30 17:24:35,240 dev_appserver.py:3105] "POST /updateworker HTTP/1.1" 302 -
WARNING  2013-05-30 17:24:35,245 taskqueue_stub.py:1980] Task task1 failed to execute. This task will retry in 0.200 seconds
...

我能做什么？谢谢你的帮助！在

Answer 1

由于任务队列任务将由应用程序生成，因此原始请求中的任何头都不会被发送。特别是，Cookies头通过应用程序的SACSIDcookie标识用户（由appengine Users API提供）。在

更新：（这是在原始帖子之后添加的。）由于没有cookies，标识用户的SACSIDcookie将不在那里，因此，decorator.oauth_required的指定将在cron作业运行时强制重定向（即HTTP 302）。在

与其尝试从decorator获取当前用户，不如将appengine用户ID传递给任务。首先获取当前用户（在装饰方法中）：

from google.appengine.api import users
# Guaranteed not to be None by the decorator
current_user = users.get_current_user()

然后在任务中传递appengine用户ID

^{pr2}$

然后在您的任务中，您可以检索user_id的抓取

# This is the 'user_id' you appended in the query string
user_id = self.request.get('user_id')

并使用它来获取该用户的凭据as is done in the decorator：

from oauth2client.appengine import CredentialsModel
from oauth2client.appengine import StorageByKeyName
# This assumes you are using the defaults for OAuth2Decorator,
# which your above code is
credentials = StorageByKeyName(
    CredentialsModel, user_id, 'credentials').get()