PyFacebook Infinite Session

Question

I am trying to set a cron task to read updates for a Facebook application. I have prompted the user to grant Offline Access permissions and i have store the session_key in the db.

I am crearing a new Facebook object and besides api and secret key I also use the session_key (previously stored in db) and the fb uid. When i am trying to create the auth token or do a API call i get a Error 104: Incorrect signature

Any ideas, experience, hints ?

Answer 1

I've never used PyFacebook. Or tried to resume sessions in this manner. But I'd imagine just storing session_key and uid is not enough. There are other params too, and a signature param that's calculated based on all the fb_* params. So you might need to store all of them.

But even so, they might only work for 20-30 minutes if you're unlucky.

Answer 2

I just wrote a blog entry about my search for something similar - need to write a Python cron script. Here's what I came up with:

#!/usr/bin/python
import os, sys, optparse, time, json
import facebook

##

USER_SESSION_FILE = os.path.expanduser('fb-user.session')
APP_KEY_FILE = os.path.expanduser('fb-app.keys')

##

def main():
    app_keys = open(APP_KEY_FILE).readlines()
    fb_api = facebook.Facebook(api_key=app_keys[0].strip(), secret_key=app_keys[1].strip())
    opts, args = parse_options()
    if args == ['init']:
        init(fb_api)
        return
    session = json.load(open(USER_SESSION_FILE))
    fb_api.uid = session['uid']
    fb_api.secret = session['secret']
    fb_api.session_key = session['session_key']

    fb_api.stream.publish(message="test from PyFacebook")


def init(fb_api):
    fb_api.auth.createToken()

    sys.stdout.write('Opening web page to add application (press ENTER when done)...')
    sys.stdout.flush()
    fb_api.login()
    raw_input()

    sys.stdout.write('Asking for offline access now...')
    sys.stdout.flush()
    fb_api.request_extended_permission('offline_access')
    raw_input()

    sys.stdout.write('And, finally, asking for permission to publish')
    sys.stdout.flush()
    fb_api.request_extended_permission('publish_stream')
    raw_input()

    fb_api.auth.getSession()

    if fb_api.session_key_expires != 0:
        print """We were granted a temporary key; please wait a minute and run `%s init` again.""" % (sys.argv[0],)
    else:
        if not os.path.exists(USER_SESSION_FILE):
            # Only set restrictive permissions when creating the file
            # ourselves.
            open(USER_SESSION_FILE, 'w').close()
            os.chmod(USER_SESSION_FILE, 0600)
        json.dump({
                   'uid': fb_api.uid,
                   'secret': fb_api.secret,
                   'session_key': fb_api.session_key,
                   },
                   open(USER_SESSION_FILE, 'w'),
                   sort_keys=True,
                   indent=4)


def parse_options():
    p = optparse.OptionParser()
    return p.parse_args()


if __name__ == '__main__':
    sys.exit(main())