ScalaEnumDeserializer.scala

import com.fasterxml.jackson.core.JsonParser
import com.fasterxml.jackson.databind.DeserializationContext
import com.fasterxml.jackson.databind.JsonDeserializer

import scala.reflect.runtime.universe._

class ScalaEnumDeserializer[T](implicit tag: TypeTag[T]) extends JsonDeserializer[T] {

  private[this] val values: Map[String, T] = {
    val knownSubclasses = tag.tpe.typeSymbol.asClass.knownDirectSubclasses.filter(_.isModuleClass)

    //sealed trait and have subclasses-objects - an enum!
    knownSubclasses.map { e =>
      val v = runtimeMirror(getClass.getClassLoader).reflectModule(e.asClass.module.asModule).instance.asInstanceOf[T]
      v.toString -> v
    }.toMap
  }

  private[this] val name = tag.tpe.typeSymbol.name.toString.trim

  override def deserialize(p: JsonParser, ctxt: DeserializationContext): T = {
    val v = p.getText()
    values.get(v) match {
      case Some(r) => r
      case None => throw new RuntimeException(s"Unknown value '${v}' for enum ${name}. Valid values are: " +
        values.keys.toList.sorted.map("'" + _ + "'").mkString(", "))
    }
  }

}