Error while calling an API using akka in scala - scala

Question

TO start with I am very new to Scala and also I don't have any Java experience also. I am trying to call an API using simple Scala code and running into the errors. Code looks like:
import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.stream.ActorMaterializer
import scala.concurrent.Future
import scala.util.{ Failure, Success }
object Client {
def main(args: Array[String]): Unit = {
implicit val system = ActorSystem()
implicit val materializer = ActorMaterializer()
// needed for the future flatMap/onComplete in the end
implicit val executionContext = system.dispatcher
val responseFuture: Future[HttpResponse] = Http().singleRequest(HttpRequest(uri = "https://akka.io"))
responseFuture
.onComplete {
case Success(res) => println(res)
case Failure(_) => sys.error("something wrong")
}
}
}
Basically, I have just copied the code from Akka documentation and trying to run it.
I get the following errors:
not found: value ActorSystem
implicit val system = ActorSystem()
not found: value ActorMaterializer
implicit val materializer = ActorMaterializer()
Cannot find an implicit ExecutionContext. You might pass
an (implicit ec: ExecutionContext) parameter to your method.
Also 'ActorMaterializer()' now seems to be deprecated. Is this the reason for errors?
Thanks in advance :)

Answer 1

You may need to add akka-streams as a dependency in your build tool.
ActorMaterializer.apply should just be a warning, unrelated to your other error. Might be worth opening an issue on github asking for updated docs for this snippet though.

Answer 2

This should get you going.
In your build.sbt
scalaVersion := "2.13.8"
val akkaVersion = "2.6.19"
val akkaHTTPVersion = "10.2.9"
libraryDependencies ++= Seq(
"com.typesafe.akka" %% "akka-stream" % akkaVersion,
"com.typesafe.akka" %% "akka-actor" % akkaVersion,
"com.typesafe.akka" %% "akka-http" % akkaHTTPVersion
)
The code below is from the latest Doc, with the added line to consume the response entity as described in the Doc.
object HttpClientSingleRequest extends App {
implicit val system: ActorSystem = ActorSystem()
import system.dispatcher
val responseFuture: Future[HttpResponse] = Http().singleRequest(HttpRequest(uri = "https://akka.io"))
responseFuture
.onComplete {
case Success(res) =>
// Even if we don’t care about the response entity, we must consume it
res.entity.discardBytes()
println(s"Success: ${res.status}")
case Failure(ex) => sys.error(s"Something wrong: ${ex.getMessage}")
}
}