I have a SharedFlow to emit user data to UI layer ...

# flow

[Simon Lin]

I have a SharedFlow to emit user data to UI layer like below,
and the user can click a button to call refresh() to update userFlow (let emit(userRepository.getUser()) call again.)
How do I implement refresh() ?

// ViewModel

val userFlow = flow {
    emit(userRepository.getUser())
}.shareIn(viewModelScope, SharingStarted.WhileSubscribed(), replay = 1)

fun refresh() {
    // How to reload user?
}

[Nick Allen]

Use a MutableSharedFlow and then you can tryEmit. Then you can build your userFlow off of that. And I always recommend using StateFlow instead of having the UI code wait for an initial value.

val refreshes = MutableSharedFlow<Unit>(
    extraBufferCapacity = 1, //hold the "event"
    onBufferOverflow = BufferOverflow.DROP_LATEST //no need to refresh if you already will
)

fun refresh() {
    refreshes.tryEmit(Unit)
}

val userFlow = refreshes //All you refresh events
    .onStart { emit(Unit) //An initial event to start
    .mapLatest { userRepository.getUser() } //mapLatest will cancel call if new refresh comes in
    .stateIn(viewModelScope, SharingStarted.WhileSubscribed(), null) //null can mean loading