before_destroy :destroyable?
  private
  def destroyable?
    article_properties.empty? || errors.add_to_base("Beeing used in article_properties")
    property_values.empty? || errors.add_to_base("Beeing used in property_values")
    cart_item_properties.empty? || errors.add_to_base("Beeing used in carts")
    order_item_properties.empty? || errors.add_to_base("Beeing used in orders")
    errors.nil?
  end