change in behaviour of POST between 1.14.0 and 1.15.0

It seems a change was introduced sometime in 1.15.0

This used to work

    fun getSessionInfo(tokenId: String): AmSession {
        logger.debug { "fetching info for session: $tokenId" }
        val (req, res, result) =
            http.request(
                method = Method.POST,
                path = "/json/sessions?_action=getSessionInfo&tokenId=$tokenId"
            )
                    .header("Accept-API-Version" to "resource=2.0")
                    .header("Content-Type" to "application/json")
                    .responseString()
        logger.debug { "\n${req.cUrlString()}\n--> $req\n$res" }
        result.fold({ d ->
            return Json().parse(d)
        }, { err ->
            throw err.exception
        })
    }

and it sent this request

$ curl -i -X POST -H "Accept-Encoding:compress;q=0.5, gzip;q=1.0" -H "Content-Type:application/json" -H "Accept:application/json" -H "Accept-API-Version:resource=2.0" https://authserver/json/sessions?_action=getSessionInfo&tokenId=d5zqRsYnIPTqXvZRZGvdEdOB9Gs.*AAJTSQACMDIAAlNLABxPWFZLMHRhMHBHeXl6YjMrQ1h5Wk5LdGJubFk9AAJTMQACMDE.*
--> "Body : (empty)"
"Headers : (4)"
Accept-Encoding : compress;q=0.5, gzip;q=1.0
Content-Type : application/json
Accept : application/json
Accept-API-Version : resource=2.0

Notice the content type is “application/json” as is expected due to it being requested in code example on line 10

however in newer versions the request is this, notice the content type header being appended for some reason, instead of overwritting

$ curl -i -X POST -H "Accept-Encoding:compress;q=0.5, gzip;q=1.0" -H "Content-Type:application/x-www-form-urlencoded; application/json" -H "Accept:application/json" -H "Accept-API-Version:resource=2.0" https://authserver/json/sessions?_action=getSessionInfo&tokenId=d5zqRsYnIPTqXvZRZGvdEdOB9Gs.*AAJTSQACMDIAAlNLABxPWFZLMHRhMHBHeXl6YjMrQ1h5Wk5LdGJubFk9AAJTMQACMDE.*
--> --> https://authserver/json/sessions?_action=getSessionInfo&tokenId=d5zqRsYnIPTqXvZRZGvdEdOB9Gs.*AAJTSQACMDIAAlNLABxPWFZLMHRhMHBHeXl6YjMrQ1h5Wk5LdGJubFk9AAJTMQACMDE.*
"Body : (empty)"
"Headers : (4)"
Accept-Encoding : compress;q=0.5, gzip;q=1.0
Content-Type : application/x-www-form-urlencoded; application/json
Accept : application/json
Accept-API-Version : resource=2.0

content type now for whatever reason is Content-Type : application/x-www-form-urlencoded; application/json

The server in this instance cant handle that, but the issue is that Fuel is doing something other than what the code tells it to do, it should send Content-Type : application/json as that is what was specified in code

[markGilchrist]

@SleeplessByte @fnunezkanut The reason this was added was to support multiple headers by the same key.

if you change your code from

.header("Accept-API-Version" to "resource=2.0")
                    .header("Content-Type" to "application/json")
                    .responseString()

to

.header(mapOf("Accept-API-Version" to "resource=2.0", "Content-Type" to "application/json"))

I believe that it will overwrite the values if that is what you require. If I have any of the above wrong then please let me know and I will investigate further

[SleeplessByte]

@kittinunf @markGilchrist

Content-Type is not a header that can be appended to. Changing this into something like

fun header(vararg pairs: Pair<String, Any>?): Request {
    headers.delete(key)
    return appendHeader(pairs)
}

fun appendHeader(pairs: Pair<String, Any>?): Request {
    pairs.filterNotNull().forEach { (key,value) ->
        if (!headers.containsKey(key)) {
            headers += Pair(key, value.toString())
        } else {
            headers[key] =  headers.getValue(key).let { "$it; $value" }
        }
    }
    return this
}

allows you to keep the old behaviour whilst supporting the new behaviour.