How to schedule an API request asynchronously for one composable screen from another composable screen? (Jetpack Compose)

The problem is how to handle data consistency, which is not directly related to jetpack compose. I suggest you solve this problem at the model level. Return flow instead of static data in the repository, and use collectAsState in the jetpack compose to monitor data changes.

It’s hard to give an example, because it depends on the type of Model layer. If it’s a database, androidx’s room library supports returning flow; if it’s a network, take a look at this.
https://gist.github.com/FishHawk/6e4706646401bea20242bdfad5d86a9e

Triggering a refresh is not a good option. It is better to maintain an ActionChannel in the repository for each list that is monitored. use the ActionChannel to modify the list locally to notify compose of the update.

For example, you can make a PagedList if the data layer is network. With onStart and onClose, channels can be added or removed from the repository, thus giving the repository the ability to update all the observed lists.

sealed interface RemoteListAction<out T> {
    data class Mutate<T>(val transformer: (MutableList<T>) -> MutableList<T>) : RemoteListAction<T>
    object Reload : RemoteListAction<Nothing>
    object RequestNextPage : RemoteListAction<Nothing>
}

typealias RemoteListActionChannel<T> = Channel<RemoteListAction<T>>

suspend fun <T> RemoteListActionChannel<T>.mutate(transformer: (MutableList<T>) -> MutableList<T>) {
    send(RemoteListAction.Mutate(transformer))
}

suspend fun <T> RemoteListActionChannel<T>.reload() {
    send(RemoteListAction.Reload)
}

suspend fun <T> RemoteListActionChannel<T>.requestNextPage() {
    send(RemoteListAction.RequestNextPage)
}

class RemoteList<T>(
    private val actionChannel: RemoteListActionChannel<T>,
    val value: Result<PagedList<T>>?,
) {
    suspend fun mutate(transformer: (MutableList<T>) -> MutableList<T>) =
        actionChannel.mutate(transformer)

    suspend fun reload() = actionChannel.reload()
    suspend fun requestNextPage() = actionChannel.requestNextPage()
}

data class PagedList<T>(
    val list: List<T>,
    val appendState: Result<Unit>?,
)

data class Page<Key : Any, T>(
    val data: List<T>,
    val nextKey: Key?,
)

fun <Key : Any, T> remotePagingList(
    startKey: Key,
    loader: suspend (Key) -> Result<Page<Key, T>>,
    onStart: ((actionChannel: RemoteListActionChannel<T>) -> Unit)? = null,
    onClose: ((actionChannel: RemoteListActionChannel<T>) -> Unit)? = null,
): Flow<RemoteList<T>> = callbackFlow {
    val dispatcher = Dispatchers.IO.limitedParallelism(1)

    val actionChannel = Channel<RemoteListAction<T>>()

    var listState: Result<Unit>? = null
    var appendState: Result<Unit>? = null
    var value: MutableList<T> = mutableListOf()
    var nextKey: Key? = startKey

    onStart?.invoke(actionChannel)

    suspend fun mySend() {
        send(
            RemoteList(
                actionChannel = actionChannel,
                value = listState?.map {
                    PagedList(
                        appendState = appendState,
                        list = value,
                    )
                },
            )
        )
    }

    fun requestNextPage() = launch(dispatcher) {
        nextKey?.let { key ->
            appendState = null
            mySend()
            loader(key)
                .onSuccess {
                    value.addAll(it.data)
                    nextKey = it.nextKey
                    listState = Result.success(Unit)
                    appendState = Result.success(Unit)
                    mySend()
                }
                .onFailure {
                    if (listState?.isSuccess != true)
                        listState = Result.failure(it)
                    appendState = Result.failure(it)
                    mySend()
                }
        }
    }

    var job = requestNextPage()

    launch(dispatcher) {
        actionChannel.receiveAsFlow().flowOn(dispatcher).collect { action ->
            when (action) {
                is RemoteListAction.Mutate -> {
                    value = action.transformer(value)
                    mySend()
                }
                is RemoteListAction.Reload -> {
                    job.cancel()
                    listState = null
                    appendState = null
                    value.clear()
                    nextKey = startKey
                    mySend()
                    job = requestNextPage()
                }
                is RemoteListAction.RequestNextPage -> {
                    if (!job.isActive) job = requestNextPage()
                }
            }
        }
    }
    launch(dispatcher) {
        Connectivity.instance?.interfaceName?.collect {
            if (job.isActive) {
                job.cancel()
                job = requestNextPage()
            }
        }
    }
    awaitClose {
        onClose?.invoke(actionChannel)
    }
}

And in repository:

val postListActionChannels = mutableListOf<RemoteListActionChannel<Post>>()

suspend fun listPost() =
    daoFlow.filterNotNull().flatMapLatest {
        remotePagingList(
            startKey = 0,
            loader = { page ->
                it.mapCatching { dao ->
                    /* dao function, simulate network operation, return List<Post> */
                    dao.listPost(page)
                }.map { Page(it, if (it.isEmpty()) null else page + 1) }
            },
            onStart = { postListActionChannels.add(it) },
            onClose = { postListActionChannels.remove(it) },
        )
    }

suspend fun markPost(title: String) =
    oneshot {
        /* dao function, simulate network operation, return Unit */
        it.markPost(title)
    }.onSuccess {
        postListActionChannels.forEach { ch ->
            ch.mutate { list ->
                list.map {
                    if (it.title == title && !it.isBookMarked)
                        it.copy(isBookMarked = true)
                    else it
                }.toMutableList()
            }
        }
    }