Rails - pass additional parameters while using redirect_to

http://stackoverflow.com/questions/5599698/rails-passing-parameters-in-a-redirect-to-is-session-the-only-way

redirect_to(new_user_path(:notice => 'Please register as a new user', :uid => 'ABCD'))

The params you want to pass are arguments to the new_user_path method, not the redirect_tomethod.