Often, the login redirection has a static redirection to say, rootpath or userpath.

When a logged out user tries to access a page that requires to be logged in, it is better, for a good user experience, to dynamically redirect them to that requested page after they logged in.

I did not find much resources on that, and the few explainations I found seemed way too unclear, instable or just didn't feel simple/good enough.

So here is what I found with Devise, which works like a charm and is really simple.

Devise has that method called stored_location_for(resource) which, as its name says, stores the location the resource (user, admin, etc.) is coming from before signing in.

By default, after signing in, Devise calls after_sign_in_path(resource) to get the path to redirect to, which more or less returns resource_path by default.

So, now we are aware of those two methods, let's simply rewrite after_sign_in_path using stored_location_for!

class ApplicationController << ActionController::Base
  protect_from_forgery

  def after_sign_in_path(resource)
  sign_in_url = url_for(:action => 'new', :controller => 'sessions', :only_path => false, :protocol => 'http')

    if request.referer == sign_in_url
      super
    else
      stored_location_for(resource) || request.referer || root_path
    end
  end
end

So here, the first step is to check if the request was originally made from were the default redirection is. If it is, let's keep the magic from Devise, and call super so we are sure we are not missing anything.

If it's not the case, we return stored_location_for to get the original request, and if it wasn't stored, we get request.referer, and finally if this is not available either, our last hope is to return to the root_path.

I had to look deep inside Devise's github to find this, and no answer on stackoverflow seemed to be using this solution, so here it is!