Scala Play在构造上读取Json和LocalDateTime

Question

I have a simple case class Location (It's pretty much the ScalaJsonCombinators tutorial)

// controller
implicit val locationWrites: Writes[Location] =
(
  (JsPath \ "latitude").write[Double] and
  (JsPath \ "longitude").write[Double]
) (unlift(Location.unapply))

implicit val locationReads: Reads[Location] =
(
  (JsPath \ "latitude").read[Double] and
  (JsPath \ "longitude").read[Double]
) (Location.apply _)

// model
case class Location(latitude: Double, longitude: Double)

object Location {
  implicit val formatter = Json.format[Location]
}

I want to set the current time on the construction, so that my Location would look like:

case class Location(latitude: Double, longitude: Double, date: LocalDateTime)

Unfortunately I can't really figure out how to use Play Json to pass LocalDateTime.now() without sending an additional field or actually how to pass the LocalDateTime in general.

The Request Body

{ 
     "latitude": ...
     "longitude": ...
}

Answer 1

Rather than passing Location.unapply / Location.apply to the FunctionalBuilder you can pass your own functions:

case class Location(latitude: Double, longitude: Double, date: LocalDateTime)

implicit val locationWrites: Writes[Location] =
(
  (JsPath \ "latitude").write[Double] and
  (JsPath \ "longitude").write[Double]
) ((l: Location) => (l.latitude, l.longitude))

implicit val locationReads: Reads[Location] =
(
  (JsPath \ "latitude").read[Double] and
  (JsPath \ "longitude").read[Double]
) ((lat: Double, lon: Double) => Location(lat, lon, LocalDateTime.now()))