Unable to locate the JsonDecoder for a type constructor containing a nested type.

[wi101]

Hello,

This issue appeared when updating to zio-json: 0.7.0.
Here is an example:

final case class Id[A](value: A)
object Id {
  implicit def decoder[A: JsonDecoder]: JsonDecoder[Id[A]] = DeriveJsonDecoder.gen[Id[A]]
}

final case class Person(name: String) extends AnyVal
object Person {
  implicit val decoder: JsonDecoder[Person] = DeriveJsonDecoder.gen
}


final case class People(ids: Id[Person])
object People {
  implicit val decoder: JsonDecoder[People] = DeriveJsonDecoder.gen
}

Error:

magnolia: could not find JsonDecoder.Typeclass for type Id[Person]
[error]     in parameter 'ids' of product type People
[error]   implicit val decoder: JsonDecoder[People] = DeriveJsonDecoder.gen

People.decoder cannot find the decoder for Id[Person].
There is an issue on finding the Id.decoder ..

when we manually add the decoder to Id companion object:

object Id {
    implicit val decoderIds: JsonDecoder[Id[Person]] = DeriveJsonDecoder.gen
}

The same error appears. But it works only when we add that decoder to People companion.

object People {
  implicit val decoderIds: JsonDecoder[Id[Person]] = Id.decoder
  implicit val decoder: JsonDecoder[People] = DeriveJsonDecoder.gen
}

[jdegoes]

/bounty $200

[algora-pbc]

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Attempt	Started (GMT+0)	Solution
🔴 @Anshgrover23	Jun 28, 2024, 4:11:00 PM	WIP
🔴 @omarnagy91	Jul 9, 2024, 4:58:42 AM	WIP

[Anshgrover23]

/attempt #1128

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• Cancel my attempt

[987Nabil]

@wi101 I am unable to reproduce What Scala version are you using? Are the definitions all in the same file? Are you sure you have no conflicting versions in your project?

[omarnagy91]

/attempt #1128

[wi101]

@987Nabil

This is the full example (the same file)

import zio.json.{DeriveJsonDecoder, JsonDecoder}

final case class Id[A](value: A)
object Id {
  implicit def decoder[A: JsonDecoder]: JsonDecoder[Id[A]] = DeriveJsonDecoder.gen[Id[A]]
}

final case class Person(name: String) extends AnyVal
object Person {
  implicit val decoder: JsonDecoder[Person] = DeriveJsonDecoder.gen
}


final case class People(ids: Id[Person])
object People {
  implicit val decoder: JsonDecoder[People] = DeriveJsonDecoder.gen
}

scalaVersion: 2.13.14
zioJsonVersion: 0.7.0