Can't set FormUrlEncoded header for ktor http client request

Ktor Version

1.1.1

Ktor Engine Used(client or server and name)

Apache

JVM Version, Operating System and Relevant Context

Ubuntu 18.04 Information:Kotlin: kotlinc-jvm 1.3.11 (JRE 1.8.0_191-8u191-b12-0ubuntu0.18.04.1-b12)

Feedback

I am trying to POST a request to an API that uses Content-Type: application/x-www-form-urlencoded.

val message = client.post<Unit> {
    url(URL("https://tapi.telstra.com/v2/oauth/token"))
    contentType(ContentType.Application.FormUrlEncoded)
    body = getAuth(client_id = "overriddenkey", client_secret = "overridenpass")
}

I get the error: io.ktor.http.UnsafeHeaderException: Header Content-Type is controlled by the engine and cannot be set explicitly

I can’t figure out how to set the headers in the client constructor. The documentation https://ktor.io/clients/http-client/calls/requests.html specifies that custom headers can be set using HttpRequestBuilder.

How do I specify the contentType and set the header data? I could not figure it out from your documentation.

[tasmalinakis]

Hi, we bumped into this problem a while ago as well. Going through the code, I believe that the current way of doing this is by using FormDataContent like so (without specifying a contentType):

body = FormDataContent(parametersOf( "client_id" to "overriddenkey", "client_secret" to "overridenpass") )

Last time I checked this was not stated somewhere in the documentation though.

[EhsanMsz]

@e5l I’m currently working on this. to override contentType, it must be removed from UnsafeHeadersArray in HttpHeaders.kt. Is it ok to remove this from UnsafeHeadersArray?