# File lib/moneta/adapters/mongo.rb, line 123
      def doc_to_value(doc)
        case doc[@type_field]
        when 'Hash'
          doc = doc.dup
          doc.delete('_id')
          doc.delete(@type_field)
          doc.delete(@expires_field)
          doc
        when 'Number'
          doc[@value_field]
        else
          doc[@value_field].to_s
        end
      end