ProtocolBufferDecodeError：截斷使用ndb.Key

Question

，當我有這樣的代碼，它用來升級GAE的Python NDB前工作：

class MyHandler(webapp2.RequestHandler): 
    def get(self,urlString): 
    resume = ndb.Key(urlsafe=urlString).get() 

現在，我有這樣的錯誤：

Traceback (most recent call last): 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1535, in __call__ 
    rv = self.handle_exception(request, response, e) 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1529, in __call__ 
    rv = self.router.dispatch(request, response) 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1278, in default_dispatcher 
    return route.handler_adapter(request, response) 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1102, in __call__ 
    return handler.dispatch() 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 572, in dispatch 
    return self.handle_exception(e, self.app.debug) 
    File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 570, in dispatch 
    return method(*args, **kwargs) 
    File "C:\xampp\htdocs\mapjobs\main.py", line 127, in get 
    resume_key = ndb.Key(urlsafe=urlString) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\ndb\key.py", line 212, in __new__ 
    self.__reference = _ConstructReference(cls, **kwargs) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\ndb\utils.py", line 136, in positional_wrapper 
    return wrapped(*args, **kwds) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\ndb\key.py", line 642, in _ConstructReference 
    reference = _ReferenceFromSerialized(serialized) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\ndb\key.py", line 774, in _ReferenceFromSerialized 
    return entity_pb.Reference(serialized) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\datastore\entity_pb.py", line 1791, in __init__ 
    if contents is not None: self.MergeFromString(contents) 
    File "C:\Program Files (x86)\Google\google_appengine\google\net\proto\ProtocolBuffer.py", line 84, in MergeFromString 
    self.MergePartialFromString(s) 
    File "C:\Program Files (x86)\Google\google_appengine\google\net\proto\ProtocolBuffer.py", line 98, in MergePartialFromString 
    self.TryMerge(d) 
    File "C:\Program Files (x86)\Google\google_appengine\google\appengine\datastore\entity_pb.py", line 1920, in TryMerge 
    d.skipData(tt) 
    File "C:\Program Files (x86)\Google\google_appengine\google\net\proto\ProtocolBuffer.py", line 524, in skipData 
    self.skip(4) 
    File "C:\Program Files (x86)\Google\google_appengine\google\net\proto\ProtocolBuffer.py", line 499, in skip 
    if self.idx + n > self.limit: raise ProtocolBufferDecodeError, "truncated" 
ProtocolBufferDecodeError: truncated 

哪些亮點可能是：

File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 570, in dispatch 
    return method(*args, **kwargs) 
File "C:\xampp\htdocs\mapjobs\main.py", line 127, in get 
    resume_key = ndb.Key(urlsafe=urlString) 

怎麼了？

Answer 1

我的猜測是，您正在通過Url參數接收密鑰作爲url安全字符串，該參數由於瀏覽器中的最大URL長度限制而被截斷。瀏覽器在實踐中限制Url長度達到最多2000個字符。看到這個問題：What is the maximum length of a URL in different browsers?

如果你的密鑰包含（多個）父鍵，那麼有可能超過2000個字符。是這樣嗎？請在創建和收到時檢查urlsafe編碼密鑰的長度。

如果是這種情況，那麼解決方法是僅使用實體的ID（或者在父鍵的情況下使用實體）並手動構建密鑰。

Answer 2

我不匹配的URL，其中前：

app = webapp2.WSGIApplication([ 
    ('/', MainHandler), 
    ('/jobs',JobsHandler), 
    ('/job/(.*)',JobHandler), 
    ('/job/(.*)/update', JobUpdateHandler), 
    ('/job/(.*)/delete', JobDeleteHandler), 
    ('/job/create', JobCreateHandler), 
    ('/resume/(.*)',ResumeHandler), 
    ('/resume/(.*)/update', ResumeUpdateHandler), 
    ('/resume/(.*)/delete', ResumeDeleteHandler), 
    ('/resume/create', ResumeCreateHandler), 
    ('/resumes',ResumesHandler), 
    ('/profile',ProfileHandler), 
    ('/profile/(.*)/update', ProfileUpdateHandler), 
], debug=True) 

請注意，我misarranged '/resume/(.*）'，因爲這應該是在底部接收urlString最後。這是它現在是什麼：

app = webapp2.WSGIApplication([ 
    ('/', MainHandler), 
    ('/jobs',JobsHandler), 
    ('/job/(.*)/update', JobUpdateHandler), 
    ('/job/(.*)/delete', JobDeleteHandler), 
    ('/job/create', JobCreateHandler), 
    ('/job/(.*)',JobHandler), 
    ('/resume/(.*)/update', ResumeUpdateHandler), 
    ('/resume/(.*)/delete', ResumeDeleteHandler), 
    ('/resume/create', ResumeCreateHandler), 
    ('/resume/(.*)',ResumeHandler), 
    ('/resumes',ResumesHandler), 
    ('/profile',ProfileHandler), 
    ('/profile/(.*)/update', ProfileUpdateHandler), 
], debug=True)