文章/答案/技术大牛

发布

社区首页 >问答首页 >AppEngine/Python:为什么没有捕捉到异常？

问AppEngine/Python:为什么没有捕捉到异常？
EN

Stack Overflow用户

提问于 2012-08-19 00:40:55

回答 1查看 229关注 0票数 3

我正在尝试编写一个Google-Appengine应用程序，当数据存储写入被禁用时，该应用程序将很好地失败

目前我的main()看起来像这样：

def main():
    make_datastore_readonly()
    try:
        run_wsgi_app(application)
    except CapabilityDisabledError:
        run_wsgi_app(NoWrite)

如果我将main设置为：

def main():
    run_wsgi_app(application)

当异常被引发时，我的应用程序显示一个回溯。

如果我将main设置为：

def main():
    run_wsgi_app(NoWrite)

它将正确地显示我的错误消息(尽管对于每个请求)。

回到我修改后的main版本，这个版本：

def main():
    make_datastore_readonly()
    try:
        run_wsgi_app(application)
    except CapabilityDisabledError:
        run_wsgi_app(NoWrite)

我没有得到我的错误消息，而是仍然得到了一个如下所示的回溯：

Traceback (most recent call last):
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/_webapp25.py", line 703, in __call__
    handler.post(*groups)
  File "/Users/kevin/Sche/main.py", line 232, in post
    me.put();
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/db/__init__.py", line 1074, in put
    return datastore.Put(self._entity, **kwargs)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/datastore.py", line 579, in Put
    return PutAsync(entities, **kwargs).get_result()
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/datastore.py", line 556, in PutAsync
    return _GetConnection().async_put(config, entities, local_extra_hook)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/datastore/datastore_rpc.py", line 1553, in async_put
    return make_put_call(base_req, pbs, extra_hook)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/datastore/datastore_rpc.py", line 1543, in make_put_call
    self.__put_hook, user_data)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/datastore/datastore_rpc.py", line 1188, in make_rpc_call
    rpc.make_call(method, request, response, get_result_hook, user_data)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/apiproxy_stub_map.py", line 519, in make_call
    self.__service, method, request, response, self.__rpc)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/api/apiproxy_stub_map.py", line 207, in Call
    function(service, call, request, response)
  File "/Users/kevin/Sche/main.py", line 18, in hook
    raise CapabilityDisabledError('Datastore is in read-only mode')
CapabilityDisabledError: Datastore is in read-only mode

所以，我的问题是，为什么没有捕捉到异常？

编辑：

此函数来自this StackOverflow answer

def make_datastore_readonly():
  """Throw ReadOnlyError on put and delete operations."""
  def hook(service, call, request, response):
    assert(service == 'datastore_v3')
    if call in ('Put', 'Delete'):
      raise CapabilityDisabledError('Datastore is in read-only mode') //Line 18
  apiproxy_stub_map.apiproxy.GetPreCallHooks().Push('readonly_datastore', hook, 'datastore_v3')

python

google-app-engine

try-catch

wsgi

回答 1

Stack Overflow用户

回答已采纳

发布于 2012-08-19 10:11:42

main函数仅注册此应用程序。因此，异常不会在main函数中引发。因此，try ... catch语句将不起作用。

处理此异常的方法是定义一个新的RequestHandler。然后，所有想要拥有此功能的请求都应该从新的RequestHandler中继承。

例如：

Class MyRequestHandler(RequestHandler):
    def get(self):
        try:
            self.get_handler()
        except CapabilityDisabledError:
            pass

class MyRequest(MyRequestHandler):
    def get_handler(self):
        # ....
        pass

票数 2

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/12020350

复制

相似问题

问AppEngine/Python:为什么没有捕捉到异常？
EN

回答 1

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问AppEngine/Python:为什么没有捕捉到异常？EN

回答 1

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问AppEngine/Python:为什么没有捕捉到异常？
EN