InvariantFunctor.scala

import org.joda.time.DateTime
import org.joda.time.format.DateTimeFormat

import argonaut._
import Argonaut._

object InvariantFunctorBug {

  case class RecordMeta(
    externalId:String,
    recordType:String,
    name:String,
    lastUpdate:DateTime,
    nextUpdate:DateTime
  )

  case class Customer(
    id: Int,
    json: CustomerJson
  )

  case class CustomerJson(
    meta: RecordMeta,
    alias: String
  )

  val dtf = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ssZ")

  implicit def DateTimeToJson: CodecJson[DateTime] =
    CodecJson(
      (d: DateTime) => jString(dtf.print(d)),
      d => for {
        dt <- d.as[String]
      } yield DateTime.parse(dt)
    )

  implicit def recordMetaCodec = casecodec5( RecordMeta.apply _ , RecordMeta.unapply _ )(
    "externalId",
    "recordType",
    "name",
    "lastUpdate",
    "nextUpdate"
  )

  implicit def CustomerJsonToJson: CodecJson[CustomerJson] = casecodec2(
    CustomerJson.apply , CustomerJson.unapply
  )(
    "meta",
    "alias"
  )

  def main( args:Array[String]): Unit = {
    println(
      CustomerJson(
        RecordMeta("","","",new DateTime,new DateTime),
        ""
      ).asJson.spaces2
    )
  }

}