Convert any Scala object to JSON

Question

I am using latest version of Play Framework and it's JSON lib like this Json.toJson(obj). But toJson is not capable of converting any Scala object to JSON, because the structure of data is unknown. Someone suggested using case convert, but here my Scala knowledge falls short. The data comes from database, but the structure of table is not known.

Where should I look further to create convert such unknown data structure to JSON?

Answer 1

Given that there is only a limited number of types you want to serialize to JSON, this should work:

object MyWriter {
  implicit val anyValWriter = Writes[Any] (a => a match {
    case v:String => Json.toJson(v)
    case v:Int => Json.toJson(v)
    case v:Any => Json.toJson(v.toString)
    // or, if you don't care about the value
    case _ => throw new RuntimeException("unserializeable type") 
  })
}

You can use it by then by importing the implicit value at the point where you want to serialize your Any:

import MyWriter.anyValWriter
val a: Any = "Foo"
Json.toJson(a)