Content-Type in a request headers

Ktor Version

1.1.4

Ktor Engine Used(client or server and name)

Apache

JVM Version, Operating System and Relevant Context

1.8, macOS Mojave and Linux Mint, IDEA 2019.1.2 CE

Feedback

I’m accessing and API that requires me to set Content-Type for all requests, but I’m getting io.ktor.http.UnsafeHeaderException: Header Content-Type is controlled by the engine and cannot be set explicitly

Current implementation:

val client = HttpClient(Apache) {
        install(JsonFeature) {
            serializer = GsonSerializer()
        }
        install(Logging) {
            level = LogLevel.HEADERS
        }
        defaultRequest {
            header("Content-Type", "application/vnd.api+json")
        }
    }

get("/test") {
            client.get<String>("url...") {
                headers {
                    // other headers
                }
            }
        }

[aajtodd]

Why can’t clients control Content-Type header? I’m not sure I understand why the engine “has” to.

It’s also confusing since the public API of HttpMessageBuilder includes a setter

Agreed we need the ability to manually control this header for a number of reasons.

[sannysoft]

I can’t use Ktor client just because I’m unable to set Content-Type. Even your examples doesn’t work:

   val message = client.post<HelloWorld> {
      url("http://127.0.0.1:8080/")
      contentType(ContentType.Application.Json)
      body = HelloWorld(hello = "world")
   }