Custom JodaTime serializer using Play Framework's JSON library?

Dominykas Mostauskis picture Dominykas Mostauskis · Aug 15, 2013 · Viewed 11.5k times · Source

How do I implement a custom JodaTime's DateTime serializer/deserializer for JSON? I'm inclined to use the Play Framework's JSON library (2.1.1). There is a default DateTime serializer, but it uses dt.getMillis instead of .toString which would return an ISO compliant String.

Writing Reads[T] amd Writes[T] for case classes seems fairly straightforward, but I can't figure out how to do the same for DateTime.

Answer

Alexey Romanov picture Alexey Romanov · Aug 16, 2013

There is a default DateTime serializer, but it uses dt.getMillis instead of .toString which would return an ISO compliant String.

If you look at the source, Reads.jodaDateReads already handles both numbers and strings using DateTimeFormatter.forPattern. If you want to handle ISO8601 string, just replace it with ISODateTimeFormat:

  implicit val jodaISODateReads: Reads[org.joda.time.DateTime] = new Reads[org.joda.time.DateTime] {
    import org.joda.time.DateTime

    val df = org.joda.time.format.ISODateTimeFormat.dateTime()

    def reads(json: JsValue): JsResult[DateTime] = json match {
      case JsNumber(d) => JsSuccess(new DateTime(d.toLong))
      case JsString(s) => parseDate(s) match {
        case Some(d) => JsSuccess(d)
        case None => JsError(Seq(JsPath() -> Seq(ValidationError("validate.error.expected.date.isoformat", "ISO8601"))))
      }
      case _ => JsError(Seq(JsPath() -> Seq(ValidationError("validate.error.expected.date"))))
    }

    private def parseDate(input: String): Option[DateTime] =
      scala.util.control.Exception.allCatch[DateTime] opt (DateTime.parse(input, df))

  }

(simplify as desired, e.g. remove number handling)

  implicit val jodaDateWrites: Writes[org.joda.time.DateTime] = new Writes[org.joda.time.DateTime] {
    def writes(d: org.joda.time.DateTime): JsValue = JsString(d.toString())
  }