python flask遇到'NoneType' object is not subscriptable错误

Question

代码基本上都是按照那本封面是狗的flask书敲的

@users.before_app_request
def before_request():
    if current_user.is_authenticated:
        current_user.ping()
        if not current_user.confirmed \
                and request.endpoint[:5] != 'user.':
            return redirect(url_for('user.unconfirmed'))

这段出错的代码也反复对比好几次，跟书上一样啊。。。。
百度也搜不到是什么问题

下面是报错信息：
求指点

---

builtins.TypeError
TypeError: 'NoneType' object is not subscriptable

Traceback (most recent call last)
This is the Copy/Paste friendly version of the traceback. You can also paste this traceback into a gist: 

Traceback (most recent call last):
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2301, in __call__
    return self.wsgi_app(environ, start_response)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2287, in wsgi_app
    response = self.handle_exception(e)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1733, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\_compat.py", line 35, in reraise
    raise value
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2284, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1807, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1710, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\_compat.py", line 35, in reraise
    raise value
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1803, in full_dispatch_request
    rv = self.preprocess_request()
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2079, in preprocess_request
    rv = func()
  File "D:\exercises\blog\app\views\users.py", line 70, in before_request
    and request.endpoint[:5] != 'user.':
TypeError: 'NoneType' object is not subscriptable

Answer 1

你把错误翻译一下，结合debug大约你就可见：

request.endpoint[:5]

这里的这个

request.endpoint

很可能为None，然后print(request.endpoint)看看结果,诶，卧槽！果然为None！！！