Question

Since Tornado adds the following query string parameter, which contains the URL of the resource that generates the redirect url, sometimes we can redirect the user to the referring page after logging in, or logging out using the string self.redirect(self.get_argument("next", "/"))

But when I use that in the following code, it didn't work. Without login, when visiting the page / test, it will be redirected to / login? Next =% 2Ftest, but the next parameter is always null and it will be redirected to the root page instead of / test.

How can I fix this problem?

code

import os
import tornado.wsgi
import tornado.web
import tornado.options
import tornado.ioloop

class BaseHandler(tornado.web.RequestHandler):
    def get_current_user(self):
        return self.get_secure_cookie("user")

class MainHandler(BaseHandler):
    @tornado.web.authenticated
    def get(self):
        self.render('index.html', user = self.current_user)

class LoginHandler(BaseHandler):
    def get(self):
        if self.get_current_user():
            self.redirect('/')
            return
        self.render('login.html')

    def post(self):
        self.set_secure_cookie("user", self.get_argument("username"))
        self.redirect(self.get_argument('next', '/'))

class LogoutHandler(BaseHandler):
    def get(self):
        if not self.get_current_user():
            self.redirect('/')
            return
        self.clear_cookie("user")
        self.redirect(self.get_argument("next", "/"))

class TestHandler(BaseHandler):
    @tornado.web.authenticated
    def get(self):
        self.write("Testing!)

settings = { 
    "static_path" : os.path.join(os.path.dirname(__file__), "static"),
    "template_path" : os.path.join(os.path.dirname(__file__), "templates"),
    "login_url" : "/login",
    "cookie_secret" : "61oETzKXQAGaYdkL5gEmGeJJFuYh7EQnp2XdTP1o/Vo=",
    "gzip" : True,
    "debug" : True,
}

application = tornado.web.Application([
    (r"/", MainHandler),
    (r"/login", LoginHandler),
    (r"/logout", LogoutHandler),
    (r"/test", TestHandler),
], **settings)

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.instance().start()