Question

I have created a facebook app on developers.facebook.com and specified a site url for my website. When users on my website login with facebook it redirects them back to the site url I specified (e.g. example.com) on the facebook app settings.

I also have a mobile web site which has facebook login but when users login from the mobile site (mobile.example.com) it still redirects to the main site (example.com).

How can I make facebook redirect to either example.com or mobile.example.com depending on where the facebook login request comes from?

Answer 1

Facebook allows you to pass a variable named state to the auth dialog. This value gets returned by Facebook on both success or failure.

The intent of the state variable is to prevent people from gaining access to your site with forged requests. However, you could add a string to the state variable unique to people coming from the mobile site. On your redirect page registered with your app, you just need to add code to examine the state variable and redirect the user if it has the “mobile” string in it.