Json4s ignoring None fields during seriallization (instead of using 'null')

Question

I am having a generic json serialization method that uses json4s. Unfortunately, it is ignoring fields if the value is None. My goal is to have

Answer 1

I assume that you would like to have Nones serialized to null within your JSON. In this case it is sufficient to use DefaultFormats.preservingEmptyValues:

import java.util.Date
import org.json4s._
import org.json4s.jackson.Serialization

object test extends App {

  implicit val f = DefaultFormats.preservingEmptyValues // requires version>=3.2.11

  case class JsonTest(x: String, y: Option[String], z: Option[Int], a: Option[Double], b: Option[Boolean], c:Option[Date], d: Option[Any])

  val v = JsonTest("test", None, None, None, None, None, None);

  // prints {"x":"test","y":null,"z":null,"a":null,"b":null,"c":null,"d":null}
  println(Serialization.write(v))
}