What's the best way to stream data to a LazyColumn...

# compose

[martmists]

What's the best way to stream data to a LazyColumn? My current code does this:

var allItems by remember { mutableStateOf(emptyList<Page>()) }

LaunchedEffect(filter) {
    println("Updating for $filter")
    val url = "<https://my.site/pages?per_page=100&search=${filter.encodeURLPath()}>"
    var checkForMore = true
    var page = 1
    val allPages = mutableListOf<Page>()

    while (checkForMore) {
        allItems = allPages

        val res = Globals.client.get("$url&page=$page")
        if (res.status != io.ktor.http.HttpStatusCode.OK) {
            checkForMore = false
            continue
        }
        val items = res.body<List<Page>>()

        if (items.isEmpty()) {
            checkForMore = false
        } else {
            allPages.addAll(items)
            page++
        }
    }

    allItems = allPages
    println("Done setting for $filter: $allPages")
}

println(allItems)

LazyColumn {
    items(allItems) { ... }
}

but for some reason when filter gets changed (from a TextField) it sometimes doesn't update properly, and although the "Done setting" println shows elements, nothing ends up being visible.

[Zach Klippenstein (he/him) [MOD]]

Please keep code snippets more than a few lines to the thread to avoid cluttering the main channel, thanks

[Zach Klippenstein (he/him) [MOD]]

After filter changes, does “Updating for …” get printed?

[ascii]

I'd sidestep this by asking why not put this into your data/network layer? It would be easier to test if this is isolated from Compose. Let JC be responsible only for UI & family. It doesn't need to, nor should, handle data retrieval except the collectAsState* bridge methods.

[ascii]

Coroutines are not uniquely tied to Compose. They can be used elsewhere too.

[myanmarking]

probably your problem has do do with concurrency. there’s nothing preventing the allIItems from being messed up due to multiple ongoing requests

[myanmarking]

do the following. update ‘allItems’ just once at the end. That should work

[myanmarking]

this is not a good architecture imo. So many things can go wrong here. 1) what if there is a network error? 2) Two filters can race for results. 3) An outdated filter can finish first, etc. You should rethink this solution

[myanmarking]

even if the network call is cancellable, you are changing the list before the call. It will 100% bug eventually

[martmists]

What would be a better approach?