scala - Which JSON library to use when storing case objects? -

i need serialize akka events json. based on "what json library use in scala?" tried several libraries. since serializer should know nothing of concrete events, events consisting of case classes , case objects should serialised using reflection. json4s seems match requirements best.

class json4seventadapter(system: extendedactorsystem) extends eventadapter {   implicit val formats = serialization.formats(fulltypehints(list(classof[evt])))   override def tojournal(event: any): = event match { case e: anyref =>   write(e).getbytes(charsets.utf_8)}  override def fromjournal(event: any, manifest: string): eventseq = event match { case e: array[byte] => {       eventseq.single(read[evt](new string(e.map(_.tochar))))}} 

the problem using json4s is, no matter implementation used deserialization of objects produces different instances. since heavily use pattern matching case object breaks our existing code.

so question is: json library used scala , akka persistence when storing case objects?

is there 1 library handles deserialization of case objects via reflection correctly? - or have workaround?

i can't comment on json4s, since i've never used it, know non-issue in play-json. like:

import play.api.libs.json._  sealed trait myeventbase case object myevent extends myeventbase  implicit val myeventbaseformat: format[myeventbase] = format(reads.stringreads.collect(validationerror("must string `myevent`") {   case "myevent" => myevent }, writes.pure("myevent")) 

in case, serialization bare string, , piggyback on built-in stringreads assert item should deserializable string, , use collect narrow down specific string. basic idea provide specific value want deserialization in reads instance. here, it's singleton case object. so, whenever deserialize myeventbase resulting in myevent, you'll same instance back.

in real world, myeventbase has other subtypes, , structure writes instance create form of type tag serialization reads instance can key off of deserialize proper subtype. like, might serialize json object instead of bare string, , object have type field identifies subtype. or use play json extensions automatically synthesize reasonable format sealed trait.