Kebs spray-json can't resolve implicit for particular case class

[dbronecki]

Following code:

  test("issue") {
    import KebsProtocol._
    val jf = implicitly[JsonFormat[Request]]
  }
  case class Request(region: String, currency: String, date: String, code: String, items: List[RequestItem])
  case class RequestItem(itemCode: String, language: String, answers: Option[List[Answer]], requirements: String, travellers: String)
  case class Answer(answer: String)

Gives compilation error:

[error] diverging implicit expansion for type spray.json.JsonFormat[SprayValueEnumJsonFormatTests.this.Request]
[error] starting with macro method jsonValueEnumFormat in trait KebsEnumFormats
[error]     val jf = implicitly[JsonFormat[Request]]

[marcin-rzeznicki]

I'm not sure if there's much I can do about it. Probably the depth of implicit search is too big for the compiler. Eg. if you change Option[List[Answer]] to List[Answer] everything is fine. Another workaround is to define implicit val requestFormat = jsonFormatN[Request] manually. It is also true that changing Answer by adding dummy field makes it compile - probably because only RootJsonFormat macro is being expanded in this case.

I do not have any idea how I could solve it. I'll leave this issue open for a while - in case someone might have better idea.

Thanks for reporting

[marcin-rzeznicki]

Looks like fb29526 magically fixed this issue. Closing 😄