如何在GAE任务队列中执行OAuth操作？

Question

我有一个简单的Google App Engine应用程序,其中包含一个/update更新YouTube播放列表的页面.它看起来像这样:

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update_playlist()工作,该方法完成其工作,但事实证明,在某些情况下,它可以运行很长一段时间,导致一个DeadlineExceededError.所以在阅读了可用的选项之后,我认为Task Queue API是要走的路(对吗？),我正在尝试使用它,遵循Python中的使用推送队列指南.

→简而言之,我分成UpdatePage了UpdatePageHandler+ UpdatePageWorker:

class UpdateHandlerPage(webapp2.RequestHandler):

    @decorator.oauth_required
    def get(self):
        taskqueue.add(url='/updateworker')

class UpdateWorkerPage(webapp2.RequestHandler):

    def post(self):
        update_result = self.update_playlist()
        ...

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

不幸的是,在进行拆分后,我的OAuth2装饰器似乎不再起作用了:

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,我会得到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!

Answer 1

由于任务队列任务将由您的应用程序生成,因此原始请求中的任何标头都不会被发送.特别是,Cookies标头通过SACSID您的应用程序的cookie 识别您的用户(由App Engine用户API提供).

更新:(这是在原始帖子之后添加的.)由于没有cookie,SACSID标识用户的cookie将不在那里,因此decorator.oauth_required指定将强制重定向(即HTTP 302)每次 cron作业运行.

您最好将App Engine用户ID传递给您的任务,而不是尝试从装饰器中获取当前用户.首先获取当前用户(在您的装饰方法中):

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App Engine用户ID

import urllib
query_string = urllib.urlencode({'user_id': current_user.user_id()})
taskqueue.add(url='/updateworker?' + query_string)

然后在你的任务中,你可以检索抓取 user_id

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

并使用它来获取用户的凭据,如在装饰器中完成:

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()