module Devise::Controllers::Helpers

def signed_in_root_path(resource_or_scope)

tries to find a resource_root_path, otherwise it uses the root_path.
The scope root url to be used when they're signed in. By default, it first 
def signed_in_root_path(resource_or_scope)
  scope = Devise::Mapping.find_scope!(resource_or_scope)
  router_name = Devise.mappings[scope].router_name
  home_path = "#{scope}_root_path"
  context = router_name ? send(router_name) : self
  if context.respond_to?(home_path, true)
    context.send(home_path)
  elsif context.respond_to?(:root_path)
    context.root_path
  elsif respond_to?(:root_path)
    root_path
  else
    "/"
  end
end