ruby on rails - Manually setting return_to with devise -

i using devise authenticate users on app. it's working great point, having trouble specific action:

view:

<p id="save"><%= link_to "save", new_save_path, :remote => true %></p> 

saves_controller.rb:

def new   if user_signed_in?     @save = save.create(:user_id => current_user.id)     render :update |page|       page.replace_html "save", "saved!"     end   else     redirect_to new_user_session_path, :notice => "you need sign in that."   end end 

as can see, because action ajax one, can't use traditional before_filter :authenticate_user! method. instead redirecting user sign in page.

the problem is, want automatically redirect user previous page when logged in.

i understand can session[:"user.return_to"] i'm having trouble setting it. how can this? or going wrong?

i believe session key :"#{scope}_return_to, :user_return_to user class.