mandubian

import play.api.libs.json._
import play.api.libs.functional.syntax._

val r = (
  (__ \ "field1").readNullable[String] and 
  (__ \ "field2").readNullable[Int]
).tupled.filter(ValidationError("unexpected result")){ 
  case( Some(x), None ) => true; 
  case ( None, Some(x) ) => true; 
  case _ => false