Is it possible to start a Coroutine in a flow operator, so that when the flow completes, the Corouti...

# coroutines

[Lukas Lechner]

Is it possible to start a Coroutine in a flow operator, so that when the flow completes, the Coroutine is cancelled as well? I somehow need access to the scope of the flow, right?

[simon.vergauwen]

You can do flow { coroutineScope { } }.

The only thing that is forbidden is emit from a different Coroutine, but following is valid.

flow {
  coroutineScope {
    launch { /** do something */ }
    while(true) {
      currentCoroutineContext().ensureActive()
      emit(1)
    }
  }
}

[Joffrey]

What is your use case, actually? You might better be served by callbackFlow (or maybe channelFlow) depending on what you're trying to do

[Lukas Lechner]

@simon.vergauwen Oh, its actually that simple 🙂 Thanks

[Lukas Lechner]

Okay, with coroutineScope , the flow suspends until the launched Coroutine has completed. How can I create a Coroutine that runs concurrently with the flow?

[Lukas Lechner]

@Joffrey My use case is that whenever someone collects from a flow that is exposed from a repository, I want to start a Coroutine that fetches data from the network and stores it in the database. The flow of the repository should emit the items that the database flow (Android Room Database) emits. So it basically should just forward the emissions from the database and also start/stop the process of updating the database on subscription/unsubscription.

[Nick Allen]

Snippet above should work for your use case. Maybe you are emitting after the coroutineScope instead of inside it?