No valid constructor

First of all: thanks for this awesome library! I hope it finds its way into core Scala proper 😃

I’m having some issues with enums that override entryName when I use them together with Spark. I think the problem is in deserializing enums. This is the relevant enum code:

sealed abstract class PhBoardingStatus(override val entryName: String) extends EnumEntry
object PhBoardingStatus extends Enum[PhBoardingStatus] {

  val values: IndexedSeq[PhBoardingStatus] = findValues

  case object All           extends PhBoardingStatus("ALL")
  case object Closed        extends PhBoardingStatus("BC")
  case object Ignored       extends PhBoardingStatus("BI")
  case object NotOpen       extends PhBoardingStatus("BN")
  case object Open          extends PhBoardingStatus("BO")
  case object Suspended     extends PhBoardingStatus("BS")
}

When using this enum in Spark code, this stacktrace gets thrown:

2017-05-16 09:22:37 WARN  org.apache.spark.scheduler.TaskSetManager:66 - Lost task 0.0 in stage 17.0 (TID 33, kl1393d4.is.klmcorp.net): java.io.InvalidClassException: com.klm.flight720.dataSources.ph.PhBoardingStatus$Closed$; no valid constructor
	at java.io.ObjectStreamClass$ExceptionInfo.newInvalidClassException(ObjectStreamClass.java:150)
	at java.io.ObjectStreamClass.checkDeserialize(ObjectStreamClass.java:790)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1775)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2000)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1924)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2000)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1924)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
	at org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:75)
	at org.apache.spark.serializer.DeserializationStream.readValue(Serializer.scala:159)
	at org.apache.spark.serializer.DeserializationStream$$anon$2.getNext(Serializer.scala:189)
	at org.apache.spark.serializer.DeserializationStream$$anon$2.getNext(Serializer.scala:186)
        ...

I assume this is because our abstract class only has a cosntructor with 1 argument, and no no-args constructor. Any idea how I can solve this?

[tsabran]

I’ve added this in the sealed abstract class instead, which I find less verbose and seems to work fine too:

    def this() = this("")

Yet I’m not familiar enough with this to understand why we need this no-param constructor and if it could be fixed directly in the EnumEntry…

[lloydmeta]

I think case objects already extend Serializable by default, so the problem might be as you said; the lack of a no-args constructor on the parent.

Perhaps something like this could work?

sealed trait PhBoardingStatus extends EnumEntry

object PhBoardingStatus extends Enum[PhBoardingStatus] {

  val values = findValues

  case object All       extends PhBoardingStatus { override val entryName = "ALL"}
  case object Closed    extends PhBoardingStatus { override val entryName = "BC" }
  case object Ignored   extends PhBoardingStatus { override val entryName = "BI" }
  case object NotOpen   extends PhBoardingStatus { override val entryName = "BN" }
  case object Open      extends PhBoardingStatus { override val entryName = "BO" }
  case object Suspended extends PhBoardingStatus { override val entryName = "BS" }
}