Rejestracja wspierana Facebookiem w Django

<iframe src="http://www.facebook.com/plugins/registration.php?
             client_id=ID_APLIKACJI_FB&
             redirect_uri=http://www.twojadomena.com/url/odbiorczy/&
             fields=name,birthday,gender,location,email"
        scrolling="auto"
        frameborder="no"
        style="border:none"
        allowTransparency="true"
        width="100%"
        height="310px">
</iframe>

from random import choice
import hashlib
import urllib2
import json
import base64
import hmac

def parse_signed_request(signed_request, app_secret):
    """Return dictionary with signed request data.
    Code taken from https://github.com/facebook/python-sdk"""
    try:
      l = signed_request.split('.', 2)
      encoded_sig = str(l[0])
      payload = str(l[1])
    except IndexError:
      raise ValueError("'signed_request' malformed")
    
    sig = base64.urlsafe_b64decode(encoded_sig + "=" * ((4 - len(encoded_sig) % 4) % 4))
    data = base64.urlsafe_b64decode(payload + "=" * ((4 - len(payload) % 4) % 4))

    data = json.loads(data)

    if data.get('algorithm').upper() != 'HMAC-SHA256':
      raise ValueError("'signed_request' is using an unknown algorithm")
    else:
      expected_sig = hmac.new(app_secret, msg=payload, digestmod=hashlib.sha256).digest()

    if sig != expected_sig:
      raise ValueError("'signed_request' signature mismatch")
    else:
      return data

def fb_registration(request):
	"""
	Register a user from Facebook-aided registration form
	"""
	if request.POST:
		if 'signed_request' in request.POST:
			# parse and check data
			data = parse_signed_request(request.POST['signed_request'], settings.FACEBOOK_CONNECT_SECRET)
			
			# lets try to check if user exists based on username or email
			try:
				check_user = User.objects.get(username=data['registration']['name'])
			except:
				pass
			else:
				return HttpResponseRedirect('/user/login/')
			
			try:
				check_user = User.objects.get(email=data['registration']['email'])
			except:
				pass
			else:
				return HttpResponseRedirect('/user/login/')
			
			# user does not exist. We create an account
			# in this example I assume that he will login via Facebook button or RPXnow
			# so no password is needed for him - using random password to make Django happy
			randompass = ''.join([choice('1234567890qwertyuiopasdfghjklzxcvbnm') for i in range(7)])
			user = User.objects.create_user(data['registration']['name'], data['registration']['email'], randompass)
			user.save()
			user = authenticate(username=data['registration']['name'], password=randompass)
			if user is not None:
				# save in user profile his facebook id. In this case for RPXNow login widget
				fbid = 'http://www.facebook.com/profile.php?id=%s' % data['user_id']
				r = RPXAssociation(user=user, identifier=fbid)
				r.save()
				login(request, user)
			return HttpResponseRedirect('/')
			
	return render_to_response('userpanel/fb_registration.html', {}, context_instance=RequestContext(request, userpanelContext(request)))