Akka HTTP POST accepted media types

[Christian Pérez-Llamas]

Hi, I am doing my first steps with Akka HTTP with no previous experience with Spray. I need to implement a POST that can accept either text/plain or application/json and returns application/json. I am using akka-http-json library for marshalling/unmarshalling json.

This is the part of the route that deals with it:

path("things") {
  post {
    decodeRequest {
        request.entity.contentType.mediaType match {
          case MediaTypes.`text/plain` =>
            import PredefinedFromEntityUnmarshallers.stringUnmarshaller
            entity(as[String]) { body => // Every line can contain things, empty lines or comments
              complete {
                Source.fromString(body).getLines
                  .map(_.trim)
                  .filterNot(line => line.isEmpty || line.startsWith("#"))
                  .toSeq
              }
            }
          case MediaTypes.`application/json` =>
            entity(as[List[Thing]]) { things =>
              complete(things.map(_.name))
            }
          case _ =>
            reject
        }
    }
  }
}

When I do a request with curl with 'Content-Type:text/csv' for example I get a:

HTTP/1.1 404 Not Found
The requested resource could not be found.

My gut intuition tells me that I am not doing the media type multiplexing the right way. What is the idiomatic way to handle different media types ?, and how can I specify the allowed ContentTypes (or media types) so the response error is more specific ?

Thank you very much,
Christian

[Konrad Malawski]

Hi, there's some things that can be improved here (I'll follow up later),

however the first thing that confused me:

You mention (and handle) text/plain everywhere, yet your CURL example is about text/csv - 

which is different so I'd expect the 404 actually.

Is that a typo or the actual question?

-- 

Cheers,

Konrad 'ktoso’ Malawski
Akka @ Lightbend

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[Christian Pérez-Llamas]

Hi, sorry, I was asking too many things and not being clear.

I am doing a curl with an intentionally unsupported content-type to see the response in those cases. I was expecting something more specific such as:

HTTP/1.1 415 Unsupported Media Type
The request's Content-Type is not supported. Expected:
application/json
text/plain

but getting "404 The requested resource could not be found." made me think that the way I am handling multiple content types is not the right way with Akka Http.

Thank you so much,
Christian

[Konrad Malawski]

Ah yes :-)

Agreed and that's because of what I hinted at "things can be improved, will follow up" in the first email :-)

Effectively the response you want is indeed produced by Akka, however only when content negotiation is left up to Akka,

whereas you basically did it manually (i.e. if doesnt match you manually reject – which results in "nothing matched... 404!").

I'll write up an example of properly doing that eventually, soon I hope, as I think it needs a proper docs page.

Thanks for your patience, will ping here :)

-- 

Cheers,

Konrad 'ktoso’ Malawski
Akka @ Lightbend

[Christian Pérez-Llamas]

Thanks Konrad, looking forward for your example.

Meanwhile I just discovered how to use reject() to be more specific, like:

reject(UnsupportedRequestContentTypeRejection(Set(
  MediaTypes.`text/plain`, ContentTypes.`application/json`
)))