Nothing except "None" returned for my Python web.py Facebook app when I turn on "OAuth 2.0 for Canvas"_问答_开发者

Nothing except "None" returned for my Python web.py Facebook app when I turn on "OAuth 2.0 for Canvas"

开发者 https://www.devze.com 2023-03-07 12:38 出处：网络

I am a beginning Facebook app developer, but I\'m an experienced developer.I\'m using web.py as my web framework, and to make matters a bit worse, I\'m new to Python.

I am a beginning Facebook app developer, but I'm an experienced developer. I'm using web.py as my web framework, and to make matters a bit worse, I'm new to Python.

I'm running into an issue, where when I try to switch over to using the newer "OAuth 2.0 for Canvas", I simply can't get anything to work. The only thing being returned in my Facebook app is "None".

My motivation for turning on OAuth 2.0 is because it sounds like Facebook is going to force it by July, and I might as well learn it now and now have to rewrite it in a few weeks.

I turned on "OAuth 2.0 for Canvas" in the Advanced Settings, and rewrote my code to look for "signed_request" that is POSTed to my server whenever my test user tries to access my app.

My code is the following (I've removed debugging statements and error checking for brevity):

#!/usr/bin/env python

import base64
import web
import minifb
import urllib
import json

FbApiKey = "AAAAAA"
FbActualSecret = "BBBBBB"
CanvasURL = "http://1.2.3.4/fb/"
RedirectURL="http://apps.facebook.com/CCCCCCCC/"
RegURL = 'https://graph.facebook.com/oauth/authorize?client_id=%s&redirect_uri=%s&type=user_agent&display=page' % (FbApiKey, RedirectURL)

urls = (
  '/fb/', 'index',
)
app = web.application(urls, locals())

def authorize():
    args = web.input()

    signed_request = args['signed_request']

    #split the signed_request via the .
    strings = signed_request.split('.')

    hmac = strings[0]
    encoded = strings[1]

    #since uslsafe_b64decode requires padding, add the proper padding
    numPads = len(encoded) % 4
    encoded = encoded + "=" * numPads
    unencoded = base64.urlsafe_b64decode(str(encoded))

    #convert signedRequest into a dictionary
    signedRequest = json.loads(unencoded)

    try:
            #try to find the oauth_token, if it's not there, then
            #redirect to the login page
            access_token = signedRequest['oauth_token']
            print(access_token)
    except:
            print("Access token not found, redirect user to login")
            redirect = "<script type=\"text/javascript\">\ntop.location.href=\"" +_RegURL + "\";\n</script>"
            print(redirect)
            return redirect

    # Do something on the canvas page
    returnString = "<html><body>Hello</body></html>"
    print(returnString)

class index:
    def GET(self):
        authorize()

    def POST(self):
        authorize()

if __name__ == "__main__":
    app.run()

For the time being, I want to concentrate on the case where the user is already logged in, so assume that oauth_token is found.

My question is: Why is my "Hello" not being outputted, and instead all I see is "None"?

It appears that I'm missing something very fundamental, because I swear to you, I've scoured the Internet for solutions, and I've read the Facebook pages on this many times. Similarly, I've found many good blogs and stackoverflow questions that document precisely how to use OAuth 2.0 and signed_request. But the fact that I am getting a proper oauth_token, but my only output is "None" makes me think there is something fundamental that I'm doing incorrectly. I realize that "None" is a special word in python, so maybe that's the cause, but I can't pin down exactly what I'开发者_运维技巧m doing wrong.

When I turn off OAuth 2.0, and revert my code to look for the older POST data, I'm able to easily print stuff to the screen.

Any help on this would be greatly appreciated!

How embarrassing!

In my authorize function, I return a string. But since class index is calling authorize, it needs to be returned from the class, not from authorize. If I return the return from authorize, it works.