Hi! I’m using AppAuth on Android to login to my backend and coroutines (ktor) on my transport layer ...

# coroutines

[Sebastien Leclerc Lavallee]

Hi! I’m using AppAuth on Android to login to my backend and coroutines (ktor) on my transport layer to call APIs on that backend. I need to pass an access token to each of my calls. Using AppAuth I refresh this token with the AuthState.performActionWithFreshTokens(callback: (freshToken: String?)) which uses a callback to give me the fresh token. And my transport service uses coroutines, something like:

class TransportService {
  suspend fun getAllTasks(): List<Task> {
    authState.performActionWithFreshToken() { freshToken ->
      return ktorClient.get<List<Task>>()
    }
  }
}

Now, I have an error where I use the ktor client: suspend function can be called only within coroutines scope . That is because the callback function is not a coroutine scope. If I create a new scope within the callback, will this work well with the main function? What can I do to keep my transport with suspend function and not use completion handler everywhere? Thanks 🙂

[streetsofboston]

suspend fun getAllTasks(): List<Task> = suspendCancellableCoroutine { cont ->
    authState.performActionWithFreshToken() { freshToken ->
      cont.resume(ktorClient.get<List<Task>>())
    }
  }

[streetsofboston]

(the key here is the call to suspendCancellableCoroutine)

[Sebastien Leclerc Lavallee]

Thanks !
I don’t see any resume function on cont which take a closure to execute more suspend function, something like :

suspend fun getAllTasks(): List<Task> = suspendCancellableCoroutine { cont ->
    authState.performActionWithFreshToken() { freshToken ->
      cont.resume() {
        var list = listOf<Task>()

        do {
          list.addAll(ktorClient.get<List<Task>>())
        }
        while(moreTask)

        return list
      }
    }
  }

It’s possible with suspendCancellableCoroutine ? Thanks

[streetsofboston]

suspend fun getAllTasks(): List<Task> = suspendCancellableCoroutine { cont ->
    authState.performActionWithFreshToken() { freshToken ->
        var list = listOf<Task>()

        do {
          list.addAll(ktorClient.get<List<Task>>())
        }
        while(moreTask)

        cont.resume(list)
      }
  }

[Sebastien Leclerc Lavallee]

But this ktorClient.get<List<Task>>() is a suspend function and when called it’s not in the coroutine scope anymore because of the callback 🤔 I have the same error

[Sebastien Leclerc Lavallee]

Maybe inside the callback I can create a new coroutine scope and call the cont.resume() when I’m finished