Deserialization of case object in Scala with JSON4S

You need to write the serializer like below:

Serializer:

case object BreedSerializer extends CustomSerializer[Breed](format => (    {      case JString(breed) =>  breed match {        case "Beagle" => Beagle        case "Mastiff" => Mastiff        case "Yorkie" => Yorkie      }      case JNull => null    },    {      case breed:Breed => JString(breed.getClass.getSimpleName.replace("$",""))    }))

Now, you will have to add this serialiser to the default formats.

import org.json4s.CustomSerializerval serializers = List(BreedSerializer)implicit lazy val serializerFormats: Formats = DefaultFormats ++ serializers

Hope this solves your problem.

You can create a CustomSerializer for Breed like you mentioned :

import org.json4s._import org.json4s.JsonDSL._import org.json4s.native.JsonMethods._import org.json4s.native.Serializationimport org.json4s.native.Serialization._object BreedSerializer extends CustomSerializer[Breed]( format => (   {    case JString("Beagle")  => Beagle    case JString("Mastiff") => Mastiff    case JString("Yorkie")  => Yorkie  }, {    case Beagle  => JString("Beagle")     case Mastiff => JString("Mastiff")    case Yorkie  => JString("Yorkie")  }  ))

Which you can use as :

val json1 = """{ "name": "Spike", "breed": "Yorkie" }"""val json2 = """{ "name": "Pluto", "breed": "Mastiff" }"""implicit val json4sFormats = Serialization.formats(NoTypeHints) + BreedSerializerval dog1 = parse(json1).extract[Dog] // Dog(Spike,Yorkie)val dog2 = parse(json2).extract[Dog] // Dog(Pluto,Mastiff)