Fields inside a fields_for block

application_helper.rb

  def sanitized_object_name(object_name)
    object_name.gsub(/\]\[|[^-a-zA-Z0-9:.]/, "_").sub(/_$/, "")
  end

  def sanitized_method_name(method_name)
    method_name ||= @method_name.sub(/\?$/,"")
  end

  def form_tag_id(object_name, method_name)
    "#{sanitized_object_name(object_name.to_s)}_#{sanitized_method_name(method_name.to_s)}"
  end