Configuring the HttpClient

Nomi does not create or configure the client. This page covers the three things the application sets up on it, and what happens when one is missing.

main.kt
val client = HttpClient {
    install(ContentNegotiation) {
        json(SharedJson)
    }
    defaultRequest {
        url("https://api.example.com/")
        contentType(ContentType.Application.Json)
    }
}

  • ContentNegotiation, matching the server’s format. Without it a request with a body fails while being prepared, and a response body fails to be read.

  • A base URL, in defaultRequest, ending in a slash if it carries a path. This is ordinary URL resolution: https://api.example.com/v1 treats v1 as a resource to be replaced, silently dropping it, whereas https://api.example.com/v1/ keeps it.

  • A Content-Type, in defaultRequest. ContentNegotiation picks its converter from the request’s content type; without one, every post, put and patch fails before reaching the network.

Mistakes

Get any of this wrong and a call throws rather than returning a CallStatus. A misconfigured client is a programming error, not a call outcome.

Mistake What is raised

No ContentNegotiation, or no Content-Type, on a request with a body

IllegalStateException, from ktor.

No ContentNegotiation, or a format the response does not match, when reading a response body

NoTransformationFoundException, from ktor.