使用get\u serving\u url\u asyn从blobstore异步服务图像时出错

Question

我正在尝试从blogstore获取图像的url。使用webapp2和python。你知道吗

我这样做：

from google.appengine.api.images import get_serving_url_async ... upload = self.get_uploads()[0] blob_key = upload.key() url = yield get_serving_url_async(blob_key, secure_url = True)

我得到错误信息：

> Traceback (most recent call last):
> 
>   File "C:\Program Files
> (x86)\Google\google_appengine\lib\webapp2-2.3\webapp2.py", line 1522,
> in __call__
> 
>     return response(environ, start_response)
> 
> TypeError: 'generator' object is not callable
> 
> ERROR    2016-04-29 20:02:28,489 wsgi.py:279] 
> 
> Traceback (most recent call last):
> 
>   File "C:\Program Files
> (x86)\Google\google_appengine\google\appengine\runtime\wsgi.py", line
> 267, in Handle
> 
>     result = handler(dict(self._environ), self._StartResponse)
> 
>   File "C:\Program Files
> (x86)\Google\google_appengine\lib\webapp2-2.3\webapp2.py", line 1524,
> in __call__
> 
>     return self._internal_error(e)(environ, start_response)
> 
>   File "C:\Program Files
> (x86)\Google\google_appengine\lib\webapp2-2.3\webapp2.py", line 1522,
> in __call__
> 
>     return response(environ, start_response)
> 
> TypeError: 'generator' object is not callable

当我使用以下工具时，一切正常：

url = get_serving_url(blob_key, secure_url = True)

我找不到获取异步下载的url的方法。你知道吗

有人知道哪里出错了吗？网络上很少有关于工作原理的信息。你知道吗

谢谢。你知道吗