Some Default formats for ReactDynamo

MyDefaultFormats.scala

import io.react2.reactdynamo._
import io.react2.reactdynamo.exceptions.ReadsException
import org.joda.time.{Period, DateTime}
import org.joda.time.format.ISODateTimeFormat

trait MyDefaultFormats {

  val fmt = ISODateTimeFormat.dateTime

  implicit object DateTimeWrites extends Writes[DateTime] {
    def writes(dt: DateTime): AttributeValue = new AttributeValue().withS(fmt print dt)
  }

  implicit object DateTimeReads extends Reads[DateTime] {
    def reads(attv: AttributeValue): DateTime =
      Option(attv.getS).map(fmt.parseDateTime).getOrElse(throw ReadsException(attv.toString))
  }

  implicit object PeriodWrites extends Writes[Period] {
    def writes(p: Period): AttributeValue = new AttributeValue().withS(p.toString)
  }

  implicit object PeriodReads extends Reads[Period] {
    def reads(attv: AttributeValue): Period =
      Option(attv.getS).map(Period.parse).getOrElse(throw ReadsException(attv.toString))
  }

  implicit object EnumWrites extends Writes[Enumeration#Value] {
    def writes(enum: Enumeration#Value): AttributeValue = new AttributeValue().withS(enum.toString)
  }

}