Scala deserializing JSON with json4s issue

Question

when I am deserializing a JSON with the following simple code usign json4s

package main.scala

import org.json4s._
import org.json4s.jackson.JsonMethods._

  object Main {

    case class Person(name: String, age: Int)

    def main(args: Array[String]): Unit = {
      val jsValue = parse("""{"name":"john", "age": 28}""")
      implicit val formats = DefaultFormats
      val p = jsValue.extract[Person]
    }
  }

Is giving the following error.

Exception in thread "main" org.json4s.package$MappingException: scala.Predef$.refArrayOps([Ljava/lang/Object;)Lscala/collection/mutable/ArrayOps; Case classes defined in function bodies are not supported.

Does anyone know why it happens?

Answer 1

As it came out in the comments, this limitation has been surpassed with newer version. However you could have made this work by moving the case class definition outside your main :

package main.scala

import org.json4s._
import org.json4s.jackson.JsonMethods._

// here!
case class Person(name: String, age: Int)

object Main {

  def main(args: Array[String]): Unit = {
    val jsValue = parse("""{"name":"john", "age": 28}""")
    implicit val formats = DefaultFormats
    val p = jsValue.extract[Person]
  }

}