Is this the correct way to attach a new `Job` to the parent context? ```val connectionJob = Job(view...

# coroutines

[reactormonk]

Is this the correct way to attach a new Job to the parent context?

val connectionJob = Job(viewModelScope.coroutineContext.job)

[Sam]

Depends what you're trying to achieve. Creating a custom Job isn't something you should need to do much, and it's very easy to get wrong. What's stopping you from just making a job with launch?

[bezrukov]

Yes, but it can only make sense in a very specific cases. The more convenient is to just
val connectionJob = viewModelScope.launch { }

[reactormonk]

So in case I need two launch, nest them inside?

[Sam]

Sure, why not 👍

[reactormonk]

So tie the knot like this?

lateinit var connectionJob: Job
                        connectionJob = viewModelScope.launch {
                            launch {
                                connection.state.collect {
                                    bluetoothConnectionState.value = it
                                    when (it?.state) {
                                        GattConnectionState.STATE_DISCONNECTED -> {
                                            connectionJob.cancel()
                                        }

                                        else -> {}
                                    }
                                }
                            }
                            launch {
                                connection.networkState.collect {
                                    networkingStateFlow.value = it
                                }
                            }
                        }

[reactormonk]

Oops, the inner launch were wrong

[Sam]

Inside the outer job, you need to leave out the viewModelScope part. The launch block creates its own scope, and you want your inner jobs to be children of that scope, instead of the outer scope.

[reactormonk]

More on the lateinit var

[reactormonk]

Sorry, slack ain't very good at properly indenting code, and I'm not sure how to left-align it in the editor window 😕

[Dmitry Khalanskiy [JB]]

Typically it's
• Highlight the code you want to indent,
• Press Shift+Tab several times.

[reactormonk]

Nope, doesn't work, as the connectionJob isn't properly wired in, gotta go with the Job

[Dmitry Khalanskiy [JB]]

`connectionJob`'s parent is certainly `viewModelScope`'s job when you create it using viewModelScope.launch {}.

[reactormonk]

connectionJob will be null inside though, so that's not gonna work out too well

[Dmitry Khalanskiy [JB]]

Do you only want to use connectionJob inside the launch?

[reactormonk]

Yeah

[Dmitry Khalanskiy [JB]]

Then you don't need it at all.

[Dmitry Khalanskiy [JB]]

viewModelScope.launch {
    val connectionScope = this
    launch {
        connection.state.collect {
            bluetoothConnectionState.value = it
            when (it?.state) {
                GattConnectionState.STATE_DISCONNECTED -> {
                    connectionScope.cancel()
                }

                else -> {}
            }
        }
    }
    launch {
        connection.networkState.collect {
            networkingStateFlow.value = it
        }
    }
}

[reactormonk]

Even better

[reactormonk]

Time to rework my code to remove a bunch of Job() usages ^^