scala - Akka-http: Accept and Content-type handling

Question

I'm trying out Akka-http and hopefully someone can shed light on a the following questions:

1. How does one create different routes based on the accept: header in the request? For example, i want one code path to handle "json" and one to handle "xml" requests (with default to "json" if header is missing)

2. In cases where I don't want the contentType to be inferred, how do i specify it? For example, in the code below I try to run the json through compactPrint() but this changes it to a string, hence "text/plain". I want to override that and tell the client it's still json.

My code is something like this;

...
path("api") {
          get {
              complete {
                getStuff.map[ToResponseMarshallable] {
                  case Right(r) if r.isEmpty => List[String]().toJson.compactPrint
                  case Right(r) => r.toJson.compactPrint
                  case Left(e) => BadRequest -> e
                }
              }
          }
        }
...

The response in this case is text/plain, since compactPrint creates a string. criticism very welcome. ;)

Answer 1

You can define Content Type as follows,

complete {
           HttpResponse(entity = HttpEntity(ContentType(MediaTypes.`application/json`), """{"id":"1"}"""))
         }

You can create your custom directive as,

  def handleReq(json: String) = {
    (get & extract(_.request.acceptedMediaRanges)) {
      r =>
        val encoding: MediaRange =
          r.intersect(myEncodings).headOption
            .getOrElse(MediaTypes.`application/json`)
        complete {
          // check conditions here
         // HttpResponse(entity = HttpEntity(encoding.specimen, json)) //
        }
    }
  }

and use the directive in route as

val route = path("api"){ handleReq(json) }