app-models-photo.rb

class Photo < ActiveRecord::Base
  extend Refile::ActiveRecord::Attachment::IDName
end

refile-activerecord-attachment-idname.rb

module Refile
  module ActiveRecord
    module Attachment
      module IDName
        def attachment(name, raise_errors: false, **options)
          super

          attacher = "#{name}_attacher"
          after_save do
            store = __send__(attacher).store
            case store
            when Refile::Backend::FileSystem
              ::File.rename store.path(@image_id), store.path(id)
            else
              fail NotImplementedError
            end
          end

          class_eval "alias #{name}_id id"
          define_method :"#{name}_id=" do |value|
            instance_variable_set :"@#{name}_id", value
          end
        end
      end
    end
  end
end