scala - Akka: How to wrap a message content into an HTTP response? -

in akka-http route specific message , want wrap content error message like:

val response:future[t] = (actor ? command).mapto[t]     response match {       case err : future[invalidrequest] =>            httpresponse(408, entity = err.map(_.tojson).????)       case r : future[t] => r.map(_.tojson)     }  case class invalidrequest(error:string)  implicit val invalidrequestformat = jsonformat1(invalidrequest) 

but doesn't work. how can map text in json format?

i think can provide generic solution trying do. can start creating method returns route follows:

def service[t:classtag](actor:actorref, command:any)  (implicit timeout:timeout,  _marshaller: toresponsemarshaller[t]):route = {   val fut = (actor ? command).mapto[serviceresponse]   oncomplete(fut){     case util.success(ir:invalidrequest) =>       complete(statuscodes.badrequest, ir)      case util.success(t:t) =>       complete(t)      case util.failure(ex) =>       complete(statuscodes.internalservererror )           }     } 

this method fires request supplied actor, via ask, , gets future representing result. uses oncomplete directive apply special handling invalidresponse case. it's important here have implicit toresponsemarshaller[t] in scope need success case.

then, let's had following classes , formatters defined:

trait serviceresponse case class foo(id:int) extends serviceresponse implicit val fooformat = jsonformat1(foo) case class invalidrequest(error:string) extends serviceresponse implicit val invalidrequestformat = jsonformat1(invalidrequest) 

you use new service method within routing tree follows:

val routes:route = {   path("api" / "foo"){     get{       service[foo](fooactor, fooactor.dofoo)     }   }   } 

the problem example not waiting completion of future before building out response. trying match on underlying type of future, eliminated erasure @ runtime, not idea try , match against in way. instead need wait until it's completed , see type behind future.