How can I feed a flow with data from another flow?...

# coroutines

[jean]

How can I feed a flow with data from another flow? Some code example :

class PaymentViewModel(...) : ViewModel() { // in an android app
    private val _state = MutableStateFlow<PaymentStatus>()
    val state = _state.asStateFlow()

    fun pay() {
        ...
    }

    private fun payWithCard {
        paymentWithCard() // returns a flow of PaymentStatus
    }

    private fun payWithApp {
        payWithApp() // returns a flow of PaymentStatus
    }
}

How can I update _state with the data coming from paymentWithCard() and paymentWithApp() ? Do I have to use collect { … } on each of them and manually update the state?

[Sabbib Chowdhury]

you can combine on both your flows.

val nums = flowOf(1, 2, 3)
val strs = flowOf("one", "two", "three")
nums.combine(strs) { a, b -> "$a -> $b" } // composed value of both flows
    .collect { println(it) }

https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/combine.html

[jean]

I need to keep the StateFlow, so I don’t think combine works in this case