Hey guys! I have a Flow and a suspend function which should return some Result value. How should I c...

# coroutines

[electrolobzik]

Hey guys! I have a Flow and a suspend function which should return some Result value. How should I collect the values from the flow to be able to return the result? If I use suspendCoroutine I can’t use suspend functions inside to call collect . What is the most correct way to do that?

private suspend fun uploadMedia(
   repository: Repository
): Result = suspendCoroutine { continuation ->
        repository.uploadMedia().collect { // <-- Can't call collect
            when (it) {
            	...
            }
        }
    }

[hfhbd]

Why do you want to use suspendCororoutine at all? It’s a wrapper for callback code. Just remove it, your function is already suspend.

[streetsofboston]

Flow.first() will do this for you

[streetsofboston]

Where Flow in your example is repository.uploadMedia()

[electrolobzik]

@streetsofboston @hfhbd The problem is that I want to handle not just one item from the flow, but the whole set. For some of them (progress updates) I will do some action, and for some (success / error) I want to finish the uploadMedia method and return Result.

[electrolobzik]

I tried to just use return in the collect block, but I get an error 'return' is not allowed here

[electrolobzik]

Looks like I found the easy solution. I was just overcomplicating this. 🫠

[electrolobzik]

Thank you for help!

[louiscad]

Also, you almost never want to use suspendCoroutine at all because it can prevent cancellation, leading to memory leaks (leaking other unrelated objects) or suspend locks.

You want to use suspendCancellableCoroutine instead, and handle cancellation correctly when the single-callback based API you're wrapping supports it.

[louiscad]

But, yeah, you just needed to call repository.uploadMedia().collect { … } here, without wrapping it.

[electrolobzik]

Thank you! @louiscad