scala akka http type mismatch - scala

Question

I created a project with open api then added a endpoint GET /product which is supposed to return a product( i am testing it so I just want it to return any product).
When I run the project I get the following error.
[error] found : org.openapitools.server.model.Product.type
[error] required: (?, ?, ?) => ?
[error] def toEntityMarshallerProduct: ToEntityMarshaller[Product] = jsonFormat3(Product)
the logs point at Product inside jsonFormat3
I noticed it's caused by the number of properties of the Product Model, if I reduce them to 3, it works ! this is weird! does anyone know how to resolve this?
this is the product model file
package org.openapitools.server.model
final case class Product (
id: Int,
name: String,
isAvailable: Boolean,
description: String,
category: String
)
this is the productAPI file
package org.openapitools.server.api
import akka.http.scaladsl.server.Directives._
import akka.http.scaladsl.server.Route
import akka.http.scaladsl.model.StatusCodes
import akka.http.scaladsl.marshalling.ToEntityMarshaller
import akka.http.scaladsl.unmarshalling.FromEntityUnmarshaller
import akka.http.scaladsl.unmarshalling.FromStringUnmarshaller
import org.openapitools.server.AkkaHttpHelper._
import org.openapitools.server.model.Product
class ProductApi(
productService: ProductApiService,
productMarshaller: ProductApiMarshaller
) {
import productMarshaller._
lazy val route: Route =
path("product" / "all") {
get {
productService.productAllGet()
}
}
}
trait ProductApiService {
def productAllGet200(responseProduct: Product)(implicit toEntityMarshallerProduct: ToEntityMarshaller[Product]): Route =
complete((200, responseProduct))
def productAllGet()(implicit toEntityMarshallerProduct: ToEntityMarshaller[Product]): Route
}
trait ProductApiMarshaller {
implicit def toEntityMarshallerProduct: ToEntityMarshaller[Product]
}
and this is the main file
import akka.actor.typed.{ActorSystem, ActorRef}
import akka.actor.typed.scaladsl.Behaviors
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Route
import akka.http.scaladsl.server.Directives._
import akka.http.scaladsl.model.StatusCodes
// for JSON serialization/deserialization following dependency is required:
// "com.typesafe.akka" %% "akka-http-spray-json" % AkkaHttpVersion
import akka.http.scaladsl.marshalling.ToEntityMarshaller
import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport._
import spray.json.DefaultJsonProtocol._
import scala.io.StdIn
import akka.util.Timeout
import scala.concurrent.duration._
import scala.concurrent.{ ExecutionContext, Future }
import org.openapitools.server.api._
import org.openapitools.server.model._
object Main extends App {
// needed to run the route
implicit val system = ActorSystem(Behaviors.empty, "product")
// implicit val materializer = ActorMaterializer()
// needed for the future map/flatmap in the end and future in fetchItem and saveOrder
implicit val executionContext = system.executionContext
object DefaultMarshaller extends ProductApiMarshaller {
def toEntityMarshallerProduct: ToEntityMarshaller[Product] = jsonFormat3(Product)
}
object DefaultService extends ProductApiService {
def productAllGet() (implicit toEntityMarshallerProduct: ToEntityMarshaller[Product]) : Route = {
val reponse = Future {
Product(1,"product",false,"desc","pizza")
}
requestcontext => {
(reponse).flatMap {
(product: Product) =>
productAllGet200(product)(toEntityMarshallerProduct)(requestcontext)
}
}
}
}
val api = new ProductApi(DefaultService, DefaultMarshaller)
val host = "localhost"
val port = 3005
val bindingFuture = Http().newServerAt(host, port).bind(pathPrefix("api"){api.route})
println(s"Server online at http://${host}:${port}/\nPress RETURN to stop...")
bindingFuture.failed.foreach { ex =>
println(s"${ex} Failed to bind to ${host}:${port}!")
}
StdIn.readLine() // let it run until user presses return
bindingFuture
.flatMap(_.unbind()) // trigger unbinding from the port
.onComplete(_ => system.terminate()) // and shutdown when done
}
I noticed it's caused by the number of properties of the Product Model, if I reduce them to 3, it works ! this is weird! does anyone know how to resolve this?

Answer 1

try it with using a Data Transfer Object (DTO) which will provide by your api and a domain model object which is handled internally.
so you will use jsonFormat3 for your DTO and have no need to jsonFormat5.
a simple mapper or helper method inner of case classes provide a smooth integration of that.
for example:
final case class Product (
id: Int,
name: String,
isAvailable: Boolean,
description: String,
category: String
) {
def toDto: ProductDTO = ProductDTO(prop0, prop1, prop2)
}
final case class ProductDTO (
prop0: X,
prop1: Y,
prop2: Z
) {
def toDomain(propA: X, propB: Y): Product = Product(id, name, isAvailable, description, category)
}
object ProductSupport extends SprayJsonSupport with DefaultJsonProtocol {
implicit val productFormat = json3Format(ProductDTO)
}