shows the diff between two versions when you use Mongoid::Versioning

mongoid version diff

def compare_to(version)
  reject_fields = ["_id", "updated_at", "version"]
  diff_array = self.versions[version-1].attributes.to_hash.to_a - self.attributes.to_hash.to_a
  diff_array.delete_if {|f| reject_fields.include?(f.first) }
  Hash[diff_array]
end