Is there a better way of writing this? `loadFavoriteStations()` returns a `Flow<List<T>>...

# android

[Rafs]

Is there a better way of writing this?
loadFavoriteStations() returns a Flow<List<T>> The first map gives me a List<T> that I need to map hence the nested map calls.

[allan.conda]

try the kotlin Result API

[Rafs]

?? @allan.conda

[allan.conda]

This article was helpful for me in understanding how to improve code like that:
https://kotlin.christmas/2019/17
A bit dated and there is now an official kotlin Result API so you don’t have to write your own Result class like in the article.
https://github.com/Kotlin/KEEP/blob/master/proposals/stdlib/result.md#limitations

[allan.conda]

basically in the end you will have more imperative, less nesting, and better error handling code

[allan.conda]

But if you just want some example how your code can be improved without much explanation, I would rewrite the code like this:

private fun loadFavoriteWeather() = viewModelScope.launch(dispatcher) {
    val favoriteStations = weatherRepository.loadFavoriteStations()
    if (favoriteStations == null) { // more fine-grained error handling
        Log.e ("Failed to load stations")
    }
    val windInfo = favoriteStations.map { weatherRepository.loadWindInfo(it.name) }
    if (windInfo == null) {
        Log.e ("Failed to wind info")
    }
}

[Dominaezzz]

Check out flatMap and onEach .

[gildor]

What is your final goal, get Flow<T>? Or Flow<List<T>>?

But in any case you need flatMap instead of map as Dominic suggested, because otherwise you getting Flow as result

[radityagumay]

flatMap can be used