module ActiveModel::Validations::Callbacks::ClassMethods

def after_validation(*args, &block)
  options = args.extract_options!
  options[:prepend] = true
  options[:if] = Array.wrap(options[:if])
  options[:if] << "!halted"
  options[:if] << "self.validation_context == :#{options[:on]}" if options[:on]
  set_callback(:validation, :after, *(args << options), &block)
end

def before_validation(*args, &block)
  options = args.extract_options!
  if options.is_a?(Hash) && options[:on]
    options[:if] = Array.wrap(options[:if])
    options[:if] << "self.validation_context == :#{options[:on]}"
  end
  set_callback(:validation, :before, *(args << options), &block)
end