akka HttpResponse read body as String scala

Question

So I have a function with this signature (akka.http.model.HttpResponse):

def apply(query: Seq[(String, String)], accept: String): HttpResponse

Answer 1

import akka.http.scaladsl.unmarshalling.Unmarshal

implicit val system = ActorSystem("System")  
implicit val materializer = ActorFlowMaterializer() 

val responseAsString: Future[String] = Unmarshal(entity).to[String]

Answer 2

Here is simple directive that extracts string from request's body

def withString(): Directive1[String] = {
  extractStrictEntity(3.seconds).flatMap { entity =>
    provide(entity.data.utf8String)
  }
}

Answer 3

Unfortunately in my case, Unmarshal to String didn't work properly complaining on: Unsupported Content-Type, supported: application/json. That would be more elegant solution, but I had to use another way. In my test I used Future extracted from entity of the response and Await (from scala.concurrent) to get the result from the Future:

Put("/post/item", requestEntity) ~> route ~> check {
  val responseContent: Future[Option[String]] =
  response.entity.dataBytes.map(_.utf8String).runWith(Sink.lastOption)

  val content: Option[String] = Await.result(responseContent, 10.seconds)
  content.get should be(errorMessage)
  response.status should be(StatusCodes.InternalServerError)
}

If you need to go through all lines in a response, you can use runForeach of Source:

 response.entity.dataBytes.map(_.utf8String).runForeach(data => println(data))

Answer 4

Here is my working example,

  import akka.actor.ActorSystem
  import akka.http.scaladsl.Http
  import akka.http.scaladsl.model._
  import akka.stream.ActorMaterializer
  import akka.util.ByteString

  import scala.concurrent.Future
  import scala.util.{ Failure, Success }

  def getDataAkkaHTTP:Unit = {

    implicit val system = ActorSystem()
    implicit val materializer = ActorMaterializer()
    // needed for the future flatMap/onComplete in the end
    implicit val executionContext = system.dispatcher

    val url = "http://localhost:8080/"
    val responseFuture: Future[HttpResponse] = Http().singleRequest(HttpRequest(uri = url))

    responseFuture.onComplete {
      case Success(res) => {
        val HttpResponse(statusCodes, headers, entity, _) = res
        println(entity)
        entity.dataBytes.runFold(ByteString(""))(_ ++ _).foreach (body => println(body.utf8String))
        system.terminate()
      }
      case Failure(_) => sys.error("something wrong")
    }


  }

Answer 5

You can also try this one also.

responseObject.entity.dataBytes.runFold(ByteString(""))(_ ++ _).map(_.utf8String) map println

Answer 6

Since Akka Http is streams based, the entity is streaming as well. If you really need the entire string at once, you can convert the incoming request into a Strict one:

This is done by using the toStrict(timeout: FiniteDuration)(mat: Materializer) API to collect the request into a strict entity within a given time limit (this is important since you don't want to "try to collect the entity forever" in case the incoming request does actually never end):

import akka.stream.ActorFlowMaterializer
import akka.actor.ActorSystem

implicit val system = ActorSystem("Sys") // your actor system, only 1 per app
implicit val materializer = ActorFlowMaterializer() // you must provide a materializer

import system.dispatcher
import scala.concurrent.duration._
val timeout = 300.millis

val bs: Future[ByteString] = entity.toStrict(timeout).map { _.data }
val s: Future[String] = bs.map(_.utf8String) // if you indeed need a `String`