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With LiveData inside a Viewmodel we use switchMap or Transformations.map like this
val recipesList = cuisineType.switchMap { repository.getDisplayRecipes(it.cuisineType).asLiveData() }
What would be the best way to do this with StateFlow? I know we can just use map like below, however this this would return me Flow<Flow<List< Recipe>>> which doesn't seem correct
val recipeListFlow = cuisineTypeStateFlow.map {
repository.getDisplayRecipes(it.cuisineType)
}
900
StateFlow is a hot flow—it remains in memory as long as the flow is collected or while any other references to it exist from a garbage collection root.
The main difference between a SharedFlow and a StateFlow is that a StateFlow takes a default value through the constructor and emits it immediately when someone starts collecting, while a SharedFlow takes no value and emits nothing by default.
A mutable state flow is created using MutableStateFlow(value) constructor function with the initial value. The value of mutable state flow can be updated by setting its value property. Updates to the value are always conflated. So a slow collector skips fast updates, but always collects the most recently emitted value.
StateFlow is like a way to use Kotlin Flow to manage and represent a state in an application. StateFlow is a type of interface, which is only a read-only and always returns the updated value. And to receive the updated value we just collect the value from the implemented Flow.
Kotlin map is a collection of key/value pairs, where each key is unique, and it can only be associated with one value. The same value can be associated with multiple keys though. We can declare the keys and values to be any type; there are no restrictions. A Kotlin map can be either mutable ( mutableMapOf) or read-only ( mapOf ).
If you are not familiar with Kotlin’s Flow operators, they work pretty much exactly like the standard Collection operators from a user perspective, except that they are performed on a Flow and they transform to a Flow. Below you can see a comparison between map on a Collection (technically on an Iterable) and on a Flow.
Since a StateFlow is a type of Flow, we have all of the Flow operators available to us. In this case we will use a variation on map called mapLatest. mapLatest works like map except that it cancels any pending transform operations. So if the Flow emits 100 values, map will map every value, while mapLatest will only map the terminal value.
Should be
val recipeListFlow = cuisineTypeStateFlow.flatMapLatest {
repository.getDisplayRecipes(it.cuisineType)
}
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