Why? Becouse i can write BaseController method like this:

  def check_params!(path, exception = "Not enough params")
    raise exception unless params.deep_symbolize_keys.path_exists?(path)
  end

    check_params!({:user => [:email]}, "No email")

    raise "No email" unless params[:user] && params[:user][:email]

/related to Ruby On Rails, i write some RESTful api app and every time will check input params.