I have the following simple code in my viewmodel:
private val _foo = MutableStateFlow(0f)
val foo = _foo.asStateFlow()
In several locations in the viewmodel _foo is updated:
_foo.update { newFloat }
I want to add a log everytime foo is updated (as I'm chasing a bug). I'm pretty sure there's a simple way to add a block of code somewhere, but I can't figure it out, nor can I find examples.
Accepted Answer
You can use onEach to perform an action for every value in the Flow:
val foo = _foo
.onEach { println(it) }
.stateIn(viewModelScope, SharingStarted.Eagerly, 0f)
onEach only returns a simple Flow, so stateIn is needed to make it a StateFlow again. It creates a new coroutine for that, which would be unnecessary when using a MutableStateFlow directly - you should probably only do it for debugging, not in your production code.
Alternatively, you can start a new Flow collection by adding this after the declaration of _foo:
init {
viewModelScope.launch { _foo.collect { println(it) } }
}
tygAug 26 at 9:31 PM
2