class ActionView::Helpers::Tags::FileField

def hidden_field_for_multiple_file(options)
  tag("input", "name" => options["name"], "type" => "hidden", "value" => "", "autocomplete" => "off")
end

def render
  include_hidden = @options.delete(:include_hidden)
  options = @options.stringify_keys
  add_default_name_and_id(options)
  if options["multiple"] && include_hidden
    hidden_field_for_multiple_file(options) + super
  else
    super
  end
end