page.rb

class Page < ActiveRecord::Base
  attr_accessible :body, :name, :slug, :image, :destroyed_at
  include DestroyedAt
  has_attached_file :image
  before_destroy :make_backup, prepend: true
  before_restore :revert_image

  private

    def make_backup
      self.image_backup = [self.image_file_name, self.image_content_type, self.image_file_size, self.image_updated_at].join(',')
    end

    def revert_image
      image_meta = self.image_backup.split(',')
      self.image_file_name = image_meta[0]
      self.image_content_type = image_meta[1]
      self.image_file_size = image_meta[2].to_i
      self.image_updated_at = Time.parse(image_meta[3])
      self.image_backup = nil
    end
end