Issue with serializing / deserializing of ADTs

Hi there 👋

I’m not sure if this a known bug / feature or whether something can be tweaked in the configuration to enable this. In cases that we have a defined implicit codec for both the sealed trait and the leaf node, serializing the leaf node will always use the implicit of the leaf node regardless if the type is specified as the ADT. Subsequently, deserialization fails if we try to deserialize it as the ADT. Example:

import com.github.plokhotnyuk.jsoniter_scala.core._

sealed trait Pet {
  val name: String
}

object Pet {
  import com.github.plokhotnyuk.jsoniter_scala.macros._
  implicit val petCodec: JsonValueCodec[Pet] = JsonCodecMaker.make

  final case class Dog(name: String) extends Pet
  object Dog {
    implicit val dogCodec: JsonValueCodec[Dog] = JsonCodecMaker.make
  }
}

object Main {
  import Pet.Dog

  def serializePet(pet: Pet): String = writeToString[Pet](pet)
  def deserializePet(json: String): Pet = readFromString[Pet](json)

  def main(args: Array[String]): Unit = {
    val json = serializePet(Dog("Lassie"))
    readFromString[Dog](json) // Works
    deserializePet(json)  // Raises error
  }
}

fails with:

Exception in thread "main" com.github.plokhotnyuk.jsoniter_scala.core.JsonReaderException: expected key: "type", offset: 0x00000007, buf:
+----------+-------------------------------------------------+------------------+
|          |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f | 0123456789abcdef |
+----------+-------------------------------------------------+------------------+
| 00000000 | 7b 22 6e 61 6d 65 22 3a 22 4c 61 73 73 69 65 22 | {"name":"Lassie" |
| 00000010 | 7d                                              | }                |
+----------+-------------------------------------------------+------------------+

Where this becomes problematic is when we have serialize / deserialize other cases classes in the codebase, some of them having Pet and some others having Dog as a parameter. E.g.,

case class Person(name: String, pet: Option[Pet])
case class DogPerson(name: String, dog: Dog)
implicit val personCodec: JsonValueCodec[Person] = JsonCodecMaker.make
implicit val dogPersonCodec: JsonValueCodec[DogPerson] = JsonCodecMaker.make

readFromString[DogPerson](writeToString(DogPerson(...))) // works
readFromString[Person](writeToString(Person(...))) // error

Is there something that can be done in this case?

[plokhotnyuk]

@kyri-petrou Thanks a bunch for your feedback! Happy coding and running with jsoniter-scala!

[kyri-petrou]

Thanks again a lot for your help! Very much appreciated