I'd like to know the simplest way to make a StateFlow directly depend on another. For example, let's...

# flow

[John Aoussou]

I'd like to know the simplest way to make a StateFlow directly depend on another. For example, let's say in my viewmodel I have:

private val _stateFlow1 = MutableStateFlow(0)

Is there a way to define _stateFlow2 so that _stateFlow2.value = _stateFlow1.value * _stateFlow1.value ?

[Stew Boling]

val _stateFlow1 = MutableStateFlow(0)
val _stateFlow2 = _stateFlow1.map { it * it }.stateIn(viewModelScope)

That is if you need _stateFlow2 to be a StateFlow otherwise you can drop stateIn()

[John Aoussou]

Don't you need a coroutine do that?

[Stew Boling]

Not externally, that is why stateIn() requires a scope so it can launch an internal coroutine context.

[John Aoussou]

Well, I had tried that but it's giving me

Suspend function 'stateIn' should be called only from a coroutine or another suspend function

[Stew Boling]

Oops wrong stateIn() there is a non-suspending one

val _stateFlow1 = MutableStateFlow(0)
val _stateFlow2 = _stateFlow1.map { it * it }.stateIn(viewModelScope, SharingStarted.Eagerly, _stateFlow1.value)

[John Aoussou]

Awesome, would never have figured out that one! 🙇‍♂️