JSON format for Single property case classes

Question

Given

case class Location(lat: Double, long: Double)
case class Resident(location: Location)

What is the easiest way of writing a JSON formatter for Resident

I am trying to use the FunctionalBuilder i.e

val residentFormats: Format[Resident] = (
(JsPath \ "location").format[Location]
) (Resident.apply, unlift(Resident.unapply))

but using it with a single property case class is turning out to be not easily possible. My subsequent attempts are tending to involve a lot of code than I think is necessary.

Would appreciate some pointers

Answer 1

Just use:

object Resident {
  implicit val format: OFormat[Resident] = Json.format[Resident]
}

Or you can split definitions:

object Resident {
  implicit val reads: Reads[Resident] = Json.reads[Resident]
  implicit val writes: OWrites[Resident] = Json.writes[Resident]
}

You can define reads and writes by yourself:

object Resident {
  implicit val reads: Reads[Resident] = json => {
    (json \ "location").validate[Location].map(Resident(_))
  }
  implicit val writes: OWrites[Resident] = resident => Json.obj("localtion" -> resident.location)
}

Note: If you need to convert name from camelCase to underscore_keys, you can define implicit JsonConfiguration:

object Resident {
  implicit val jsonConfig = JsonConfiguration(SnakeCase)
  implicit val format: OFormat[Resident] = Json.format[Resident]
}