Migration Guide from Spray
==========================

General notes
-------------

Features which are not ported to the akka-http:

- ``respondWithStatus`` also known as ``overrideStatusCode`` has not been forward ported to Akka HTTP,
  as it has been seen mostly as an anti-pattern. More information here: https://github.com/akka/akka/issues/18626
- ``respondWithMediaType`` was considered an anti-pattern in spray and is not ported to Akka HTTP.
  Instead users should rely on content type negotiation as Akka HTTP implements it.
  More information here: https://github.com/akka/akka/issues/18625
- :ref:`registeringCustomMediaTypes` changed from Spray in order not to rely on global state.

Removed HttpService
-------------------

Spray’s ``HttpService`` was removed. This means that scala code like this::

    val service = system.actorOf(Props(new HttpServiceActor(routes)))
    IO(Http)(system) ! Http.Bind(service, "0.0.0.0", port = 8080)

needs to be changed into::

    Http().bindAndHandle(routes, "0.0.0.0", port = 8080)

Changes in Marshalling
----------------------

Marshaller.of can be replaced with ``Marshaller.withFixedContentType``.

Was::

    Marshaller.of[JsonApiObject](`application/json`) { (value, contentType, ctx) =>
      ctx.marshalTo(HttpEntity(contentType, value.toJson.toString))
    }

Replace with::

    Marshaller.withFixedContentType(`application/json`) { obj =>
      HttpEntity(`application/json`, obj.toJson.compactPrint)
    }

Akka HTTP marshallers support content negotiation, now it's not necessary to specify content type
when creating one “super” marshaller from other marshallers:

Before::

    ToResponseMarshaller.oneOf(
      `application/vnd.api+json`,
      `application/json`
    )(
      jsonApiMarshaller,
      jsonMarshaller
    }

After::

    Marshaller.oneOf(
      jsonApiMarshaller,
      jsonMarshaller
    )

Changes in Unmarshalling
------------------------

Akka Http contains a set of predefined unmarshallers. This means that scala code like this::

    Unmarshaller[Entity](`application/json`) {
      case HttpEntity.NonEmpty(contentType, data) =>
        data.asString.parseJson.convertTo[Entity]
    }

needs to be changed into::

    Unmarshaller
      .stringUnmarshaller
      .forContentTypes(`application/json`)
      .map(_.parseJson.convertTo[Entity])

Changes in MediaTypes
---------------------

``MediaType.custom`` can be replaced with specific methods in ``MediaType`` object.

Was::

    MediaType.custom("application/vnd.acme+json")

Replace with::

    MediaType.applicationWithFixedCharset("application/vnd.acme+json", HttpCharsets.`UTF-8`)

Changes in Rejection Handling
-----------------------------

``RejectionHandler`` now uses a builder pattern – see the example:

Before::

    def rootRejectionHandler = RejectionHandler {
      case Nil =>
        requestUri { uri =>
          logger.error("Route: {} does not exist.", uri)
          complete((NotFound, mapErrorToRootObject(notFoundError)))
        }
      case AuthenticationFailedRejection(cause, challengeHeaders) :: _ => {
        logger.error(s"Request is rejected with cause: $cause")
        complete((Unauthorized, mapErrorToRootObject(unauthenticatedError)))
      }
    }


After::

    RejectionHandler
    .newBuilder()
    .handle {
      case AuthenticationFailedRejection(cause, challengeHeaders) =>
        logger.error(s"Request is rejected with cause: $cause")
        complete((Unauthorized, mapErrorToRootObject(unauthenticatedError)))
    .handleNotFound { ctx =>
      logger.error("Route: {} does not exist.", ctx.request.uri.toString())
      ctx.complete((NotFound, mapErrorToRootObject(notFoundError)))
    }
    .result()
    .withFallback(RejectionHandler.default)

Changes in HTTP Client
----------------------

The Spray-client pipeline was removed. Http’s ``singleRequest`` should be used instead of ``sendReceive``::

    //this will not longer work
    val token = Authorization(OAuth2BearerToken(accessToken))
    val pipeline: HttpRequest => Future[HttpResponse] = (addHeader(token) ~> sendReceive)
    val patch: HttpRequest = Patch(uri, object))

    pipeline(patch).map { response ⇒
        …
    }

needs to be changed into::

    val request = HttpRequest(
      method = PATCH,
      uri = Uri(uri),
      headers = List(Authorization(OAuth2BearerToken(accessToken))),
      entity = HttpEntity(MediaTypes.`application/json`, object)
    )

    http.singleRequest(request).map {
      case … => …
    }

Changes in Headers
------------------

All HTTP headers have been moved to the ``akka.http.scaladsl.model.headers._`` package.


Changes in form fields and file upload directives
-------------------------------------------------

With the streaming nature of http entity, it’s important to have a strict http entity before accessing
multiple form fields or use file upload directives.
One solution might be using next directive before working with form fields::

    val toStrict: Directive0 = extractRequest flatMap { request =>
      onComplete(request.entity.toStrict(5.seconds)) flatMap {
        case Success(strict) =>
          mapRequest( req => req.copy(entity = strict))
        case _ => reject
      }
    }

And one can use it like this::

    toStrict {
      formFields("name".as[String]) { name =>
      ...
      }
    }