Pre-loading polymorphic associations for Atom feeds

app/models/concerns/paginable.rb

@@ -0,0 +1,7 @@
+module Paginable
+  extend ActiveSupport::Concern
+
+  included do
+    scope :paginate_by_max_id, -> (limit, max_id) { order('id desc').limit(limit).where(max_id.nil? ? '1=1' : ['id < ?', max_id]) }
+  end
+end