class ActiveRecord::Base

def self.validates_path(*args)
  configuration = args.extract_options!
  validates_each(args, configuration) do |record, attr_name, value|
    page = Page.find_by_path(value)
    record.errors.add(attr_name, :page_not_found, :default => configuration[:message]) if page.nil? || page.is_a?(FileNotFoundPage)
  end
end