title: Rails 3 : before_filter on an external link
body: <p>I don't know if I'm thinking the right way or not.</p>
  
  <p>In my rails app, I use facebook authentication with Omniauth. </p>
  
  <p>I have 2 different links "Sign In" (both of them target to auth/facebook with callback authentications/create). One should redirect to the user profile (users/show) and the other one to a post creation (posts/new).</p>
  
  <p>I think a good way to do that is to store the path (users/show) or (posts/new) when the user is clicking on one of the "sign in" links, and then redirect to this path on authentications/create method. I thought about before_filter on "auth/facebook". </p>
  
  <p>But auth/facebook is an external link to facebook and not a regular action. So how can I do that ?  </p>