I ve got a bit of a dumb question Using dagger for DI in Kto kotlinlang #ktor

fun Application.configureRouting() {

    // Starting point for a Ktor app:
    routing {


        get("/") {
            call.respondText("Hello World!")
        }

There's no 'class' to hold an

@Inject lateinit var

Sure, I can pass my dependencies to the

configureRouting()

function, but that's called from:

fun main() {
    embeddedServer(Netty, port = 8080, host = "0.0.0.0", watchPaths = listOf("classes")) {
        configureRouting()
    }.start(wait = true)
}

I don't have the terminology to correctly phrase the question but.. Where's the 'injection point' for a route, if I'm using Dagger?

Joost Klitsie

04/25/2021, 8:43 AM

Even though this might not be a satisfactory answer: Perhaps you can look at different injection frameworks. I use Kodein because it has Ktor support, it is very easy to use.

Tim Malseed

04/25/2021, 12:23 PM

Yeah, I could - I guess I'm more interested in understanding how I'd solve this problem though. I guess Ktor uses some sort of functional programming paradigm that I'm not used to. So I'm curious if a function has many dependencies, if there's some idiomatic way that those dependencies can be fulfilled without having to manually pass them down the call hierarchy. Obviously this is possible and this is what some of the alternative injection libraries provide. I wonder how this problem is solved in general.

carrot

04/25/2021, 12:29 PM

I don't actually use Dagger in this project, but we could use it if we needed to - we have a small extension function and an interface to split out "handlers", which would be fine with

@Inject

The code samples aren't complete but hopefully it helps a little https://gist.github.com/CarrotCodes/f8d88b54a4cbbc60a411835775cbd60e

Tim Malseed

04/25/2021, 12:38 PM

Thanks, I'll have a look

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