How to keep an active subscription to the channel?...

# coroutines

[aaverin]

How to keep an active subscription to the channel?
Documentation doesn’t mention BroadcastChannel/ConflatedBroadcastChannel and I need to keep active subscription to one of those

[Seri]

https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.experimental.channels/-broadcast-channel/open-subscription.html

[aaverin]

Looks like it doesn’t stay active because I get data only once

[aaverin]

myBroadcastChannel.openSubscription().consume {
                for (value in this) {
                    process(value)
                }
            }

[Seri]

What does your code look like?

[Seri]

ah, use consumeEach

[aaverin]

Tried, same result

[aaverin]

I have a callback when data changes in database, and I send it to a broadcast channel

[aaverin]

I listen to the channel in my presenter

[aaverin]

I see that data changes and event is pushed to brodscast, but subscription doesn’t kick in anymore

[aaverin]

only once

[Seri]

Something like this should work:

for (i in listener.openSubscription()) {
    println("The counter is $i")
}

[Seri]

or

listener.consumeEach {
    println("The counter is $it")
}

[aaverin]

I think I tried all options already, same result

[aaverin]

it’s quite confusing though, with so many variants to subscribe to coroutine

[Seri]

I had a sample script I was working through yesterday that used ConflatedBroadcastChannel: https://kotlinlang.slack.com/archives/C1CFAFJSK/p1535568252000100?thread_ts=1535563475.000100&cid=C1CFAFJSK

[aaverin]

Hmm
My code is now spread among several classes
but general idea is, I create ConflatedBroadcastChannel() and save it into variable.
Then I subscribe to my database updates and when I get data I send it to that channel
On the client side, I get what’s in that variable, and try to subscribe

[aaverin]

So first time I get data from database subscription works fine

[aaverin]

but when I change and get updates, subscription to broadcast doesn’t kick in anymore

[aaverin]

Debugging, I see that data is pushed to the correct broadcastChannel

[aaverin]

ok, I fixed it

[aaverin]

thanks for ideas 😃

[aaverin]

It was running in async coroutine and forgot to do await()

[Seri]

ah, alright!

[louiscad]

@aaverin Remember to use withContext in place of async whenever possible (i.e. as long as you don't need to parallelize work in a coroutine)