Spray.io: mapping request from text/json to application/json

Question

I am trying to replace a Jetty-based back-end by a pure spray-can + spray-routing one.

The front-end posts JSON content using the text/json media type. I've never had any problems with this with Jetty. I have just realized that it is not a standard type thanks to spray, which only accepts the correct and standard application/json media type.

Is there any easy way to map one to the other at the server side? I would really like to avoid having to introduce an ad-hoc release of the client side of the application to deal with this. Of course, I will make the change for the next scheduled release, but for now I need a "quick and dirty" fix.

I have tried changing the header from text/json to application/json using the following function:

def correctJsonHeaders(req:spray.http.HttpRequest) = {
  val tweakedHeaders = req.headers.map{ hdr =>
    if(hdr.name == "Content-Type" && hdr.value == "text/json")
      `Content-Type`(`application/json`)
    else
      hdr
  }
  req.copy(headers = tweakedHeaders)
}

in my route directive, like so:

path("route"){
  mapRequest(correctJsonHeaders){
    post{
      respondWithMediaType(`application/json`) {
        handleWith{ x:TypeThatUnmarshallsFromJson =>
          bizLogicReturningAJsonString(x)
        }
      }
    }
  }
}

Although the header is correctly changed, I still get a 415 error (which goes away if I change the media type to application/json at the client)

Eduardo Eduardo · Accepted Answer · 2014-01-26T11:40:59

After reading the documentation on the spray-http Content-Type Header, I changed my function to:

def correctJsonHeaders(req:spray.http.HttpRequest) = {
  if(req.headers.exists(hdr => hdr.name == "Content-Type" && hdr.value == "text/json")){
    val tweakedEntity = spray.http.HttpEntity(`application/json`, req.entity.data)
    req.copy(entity = tweakedEntity)
  }
  else req
}

which seems to work. The trick was to change the HttpEntity, instead of the header.

Spray.io: mapping request from text/json to application/json

2 Answers