circeMagic.scala

scala> import io.circe._, io.circe.generic.auto._, io.circe.jawn._, io.circe.syntax._
import io.circe._
import io.circe.generic.auto._
import io.circe.jawn._
import io.circe.syntax._

scala> import io.circe._
import io.circe._

scala> import io.circe.generic.auto._
import io.circe.generic.auto._

scala> import io.circe.jawn._
import io.circe.jawn._

scala> import io.circe.syntax._
import io.circe.syntax._

scala> case class RecordA(name: String, value: Int)
defined class RecordA

scala> case class RecordB(name: String, recordA: RecordA)
defined class RecordB

scala> case class Master(a: Set[RecordA], b: Set[RecordB])
defined class Master

scala> Master(Set(RecordA("hello", 1)), Set(RecordB("world", RecordA("foo", 42))))
res1: Master = Master(Set(RecordA(hello,1)),Set(RecordB(world,RecordA(foo,42))))

scala> res1.asJson
res2: io.circe.Json =
{
  "b" : [
    {
      "recordA" : {
        "value" : 42,
        "name" : "foo"
      },
      "name" : "world"
    }
  ],
  "a" : [
    {
      "value" : 1,
      "name" : "hello"
    }
  ]
}

scala> decode[Master](res2.toString)
res4: cats.data.Xor[io.circe.Error,Master] = Right(Master(Set(RecordA(hello,1)),Set(RecordB(world,RecordA(foo,42)))))