CODEWITHSUNDEEP
pythontornado
tywtyw2002
tywtyw2002

Reputation: 167

How does tornado stop current request handler?

There a some subclass inheritance ManageHandler, and each sub class need to do private check. So, I write private_auth and let it to do the private check in the __init__, and call it before the GET/POST method.

If failed the private check, just return 404 error. However, it not work. So how to stop the request and return the error page?

My code posted below:

class ManageHandler(BaseHandler):

    def __init__(self, *argc, **argkw):
        super(ManageHandler, self).__init__(*argc, **argkw)
        self.private_auth()


    def private_auth(self):
        self.user = self.get_secure_cookie("user")
        self.private = self.UserModel.get_user_level_by_name(self.user)

        #not login
        if self.private == -1:
            return 

        if self.private != 4:
            self.render("404.html")
            self.finish()


    @tornado.web.authenticated
    def get(self, argkw={}):
            pass

Tornado report this error.

[E 140321 02:06:04 iostream:357] Uncaught exception, closing connection.
    Traceback (most recent call last):
      File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 354, in wrapper
        callback(*args)
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
        raise_exc_info(exc)
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
        ret = fn(*args, **kwargs)
      File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 328, in _on_headers
        self.request_callback(self._request)
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 1651, in __call__
        handler = spec.handler_class(self, request, **spec.kwargs)
      File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 23, in __init__
        self.private_auth()
      File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 36, in private_auth
        self.finish()
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 837, in finish
        self.flush(include_footers=True)
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 784, in flush
        for transform in self._transforms:
    TypeError: 'NoneType' object is not iterable
[E 140321 02:06:04 ioloop:491] Exception in callback <functools.partial object at 0x10c63e1b0>
    Traceback (most recent call last):
      File "/Library/Python/2.7/site-packages/tornado/ioloop.py", line 477, in _run_callback
        callback()
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
        raise_exc_info(exc)
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
        ret = fn(*args, **kwargs)
      File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 354, in wrapper
        callback(*args)
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
        raise_exc_info(exc)
      File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
        ret = fn(*args, **kwargs)
      File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 328, in _on_headers
        self.request_callback(self._request)
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 1651, in __call__
        handler = spec.handler_class(self, request, **spec.kwargs)
      File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 23, in __init__
        self.private_auth()
      File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 36, in private_auth
        self.finish()
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 837, in finish
        self.flush(include_footers=True)
      File "/Library/Python/2.7/site-packages/tornado/web.py", line 784, in flush
        for transform in self._transforms:
    TypeError: 'NoneType' object is not iterable

Upvotes: 0

Views: 1287

Answers (1)

A. Jesse Jiryu Davis
A. Jesse Jiryu Davis

Reputation: 24017

Tornado isn't designed to do authentication and other operations in RequestHandler.__init__. That's why you get an exception when you call self.finish from __init__: the RequestHandler isn't ready to run finish yet.

Instead, override get_current_user(). The basic instructions are here:

http://tornado.readthedocs.org/en/latest/web.html#tornado.web.RequestHandler.get_current_user

And an example is here:

http://technobeans.wordpress.com/2012/08/14/tornado-authentication/

In your get_current_user(), don't set self.user and self.private, just return a tuple. Something like this:

def get_current_user(self):
    private = -1
    user = self.get_secure_cookie("user")
    if user:
        private = self.UserModel.get_user_level_by_name(self.user)

    return (user, private) if private == 4 else None

Tornado will handle the rest. In your get() method, the current (user, private) tuple will be set in self.current_user.

Upvotes: 2

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