unmarshall nested json in spray-json - akka

Question

Using spray-json (as I'm using spray-client) in order to get a latitude,longitude object from the google maps API I need to have the whole response structure set up:
case class AddrComponent(long_name: String, short_name: String, types: List[String])
case class Location(lat: Double, lng: Double)
case class ViewPort(northeast: Location, southwest: Location)
case class Geometry(location: Location, location_type: String, viewport: ViewPort)
case class EachResult(address_components: List[AddrComponent],
formatted_address: String,
geometry: Geometry,
types: List[String])
case class GoogleApiResult[T](status: String, results: List[T])
object AddressProtocol extends DefaultJsonProtocol {
implicit val addrFormat = jsonFormat3(AddrComponent)
implicit val locFormat = jsonFormat2(Location)
implicit val viewPortFormat = jsonFormat2(ViewPort)
implicit val geomFormat = jsonFormat3(Geometry)
implicit val eachResFormat = jsonFormat4(EachResult)
implicit def GoogleApiFormat[T: JsonFormat] = jsonFormat2(GoogleApiResult.apply[T])
}
import AddressProtocol._
Is there any way I can just get Location from the json in the response and avoid all this gumph?
The spray-client code:
implicit val system = ActorSystem("test-system")
import system.dispatcher
private val pipeline = sendReceive ~> unmarshal[GoogleApiResult[EachResult]]
def getPostcode(postcode: String): Point = {
val url = s"http://maps.googleapis.com/maps/api/geocode/json?address=$postcode,+UK&sensor=true"
val future = pipeline(Get(url))
val result = Await.result(future, 10 seconds)
result.results.size match {
case 0 => throw new PostcodeNotFoundException(postcode)
case x if x > 1 => throw new MultipleResultsException(postcode)
case _ => {
val location = result.results(0).geometry.location
new Point(location.lng, location.lat)
}
}
}
Or alternatively how can I use jackson with spray-client?

Answer 1

Following jrudolph's advice to json-lenses I also got in quite a bit of fiddling but finally got things to work. I found it quite difficult (as a newbie) and also I am sure this solution is far from the most elegant - nevertheless I think this might help people or inspire others for improvements.
Given JSON:
{
"status": 200,
"code": 0,
"message": "",
"payload": {
"statuses": {
"emailConfirmation": "PENDING",
"phoneConfirmation": "DONE",
}
}
}
And case class for unmarshalling statuses only:
case class UserStatus(emailConfirmation: String, phoneConfirmation: String)
One can do this to unmarshal response:
import scala.concurrent.Future
import spray.http.HttpResponse
import spray.httpx.unmarshalling.{FromResponseUnmarshaller, MalformedContent}
import spray.json.DefaultJsonProtocol
import spray.json.lenses.JsonLenses._
import spray.client.pipelining._
object UserStatusJsonProtocol extends DefaultJsonProtocol {
implicit val userStatusUnmarshaller = new FromResponseUnmarshaller[UserStatus] {
implicit val userStatusJsonFormat = jsonFormat2(UserStatus)
def apply(response: HttpResponse) = try {
Right(response.entity.asString.extract[UserStatus]('payload / 'statuses))
} catch { case x: Throwable =>
Left(MalformedContent("Could not unmarshal user status.", x))
}
}
}
import UserStatusJsonProtocol._
def userStatus(userId: String): Future[UserStatus] = {
val pipeline = sendReceive ~> unmarshal[UserStatus]
pipeline(Get(s"/api/user/${userId}/status"))
}