Json body converted to sealed trait - json

Question

I have a Play! endpoint which can receive a json body as 3 or 4 forms (I tried using generic type, but not working).
Controller:
def getChartData = Action.async(parse.json) { request =>
// ERROR: can not cast JsValue to type ChartDataRequest (which is sealed trait)
service.getChartData(request.body.asInstanceOf[ChartDataRequest]).map {
data => Ok(Json.toJson(data))
}.recover {
case _ => InternalServerErrror
}
}
Service:
def getChartData(request: ChartDataRequest): Future[data_type] = {
if (request.isInstanceOf[PieChartRequest]) {
//
} else if (request.isInstanceOf[BarChartRequest]) {
//
} else {
//
}
}
dtos:
sealed trait ChartDataRequest
final case class PieChartRequest(field1: String, field2: String, ....)
extends ChartDataRequest
final case class BarChartRequest(field1: String, field2: String, ....)
extends ChartDataRequest
I found here the solution to use sealed traits, but can't do it well.
In this point, I can not convert the JsValue to ChartDataRequest type. I can use a field "classType" in my json and then using the match pattern to create the specified object (PieDataRequest or BarDataRequest) but I think this is not the best solution.
Inside all my controller methods where I send objects as json body, I use the play validator, but have the same problem, and I removed it from code.
// ChartDataRequest can have PieDataRequest or BarDataRequest type
request.body.validate[ChartDataRequest] match {
case JsSuccess(value, _) => // call the service
case JsError(_) => Future(BadRequest("Invalid json body"))
}
thanks

Answer 1

You can follow this:
sealed trait ChartDataRequest
final case class PieChartRequest(field1: String) extends ChartDataRequest
final case class BarChartRequest(field2: String) extends ChartDataRequest
final case object WrongData extends ChartDataRequest
import play.api.libs.json._
import play.api.libs.functional.syntax._
implicit val ChartDataRequests: Reads[ChartDataRequest] = {
val pc = Json.reads[PieChartRequest]
val bc = Json.reads[BarChartRequest]
__.read[PieChartRequest](pc).map(x => x: ChartDataRequest) |
__.read[BarChartRequest](bc).map(x => x: ChartDataRequest)
}
def getChartData(request: ChartDataRequest) = {
request match {
case _: PieChartRequest =>
Future("PieChartRequest")(defaultExecutionContext)
case _: BarChartRequest =>
Future("BarChartRequest")(defaultExecutionContext)
case _ =>
Future("WrongData")(defaultExecutionContext)
}
}
def getChartDataAction = Action.async(parse.json) { request =>
// you can separate this to a new function
val doIt = request.body.asOpt[JsObject].fold[ChartDataRequest](
WrongData
){
jsObj =>
jsObj.asOpt[ChartDataRequest].fold[ChartDataRequest](
WrongData
)(identity)
}
getChartData(doIt).map {
data => Ok(Json.toJson(data))
}(defaultExecutionContext).recover {
case _ => InternalServerError
}(defaultExecutionContext)
}