Question

I am hosting a Facebook app on Google app engine, I need to make sure the user is logged into facebook before anything.

What I can currently do is display facebook’s log in button using fbxml, but I prefer the user would be redirected to Facebook’s log in page if he wasn’t logged in, then back to my app’s main page, this way I can make sure that the user is logged in before doing anything.

I am new to Facebook apps, I read here that I can redirect the user to

https://www.facebook.com/dialog/oauth?client_id=YOUR_APP_ID&redirect_uri=YOUR_URL

in order to authenticate him. But using GAE’s self.redirect(url) doesn’t work, the page stays the same. I was hoping I could do something like this in my handler:

if u'signed_request' in self.request.POST:
        facebook.load_signed_request(self.request.get('signed_request'))
        if not facebook.user_id:
            self.redirect("https://www.facebook.com/dialog/oauth?"+
                          "client_id={0}&redirect_uri={1}"
                          .format(FACEBOOK_APP_ID, EXTERNAL_HREF))
            return

but as i said earlier this doesn’t work.

Answer 1

I’m assuming by ‘Facebook App’ you mean a Canvas App – so something that will live at https://apps.facebook.com/YOUR_NAMESPACE from a user perspective?

If so, you’ll need to add the redirect via Javascript using window.top, as your app is loaded in an iframe. See https://developers.facebook.com/docs/appsonfacebook/tutorial/ and search for ‘top’, then view the example toward the end of the page.