I tried searching but didn’t find anything that he...

# compose

[wasyl]

I tried searching but didn’t find anything that helps and I’m confused. Should I expect the views to change/recompose when passing @Model into another @Composable function? Something like:

@Composable
fun App() {
    val appState = +memo {
        ParentModel(
            listOf(
                ChildModel("Item 1", false),
                ChildModel("Item 2", true)
            )
        )
    }
    Column {
        appState.childModels.forEach { item ->
            Item(item)
        }
    }
}

@Composable
fun Item(item: ChildModel) {
    ListItem(
        text = { Text(item.description) },
        trailing = {
            Checkbox(
                checked = item.checked,
                onCheckedChange = { item.checked = it })
        }
    )
}

@Model
data class ParentModel(
    var childModels: List<ChildModel>
)

@Model
data class ChildModel(
    var description: String,
    var checked: Boolean
)

?

[wasyl]

I think I tried everything, and the only thing that triggers the update is when I introduce some completely irrelevant state in the Item function and change it as well

[George Mount]

If the problem is that when you update the list (add/remove items) you aren't seeing recomposition, you should be using a ModelList instead listOf. Try replacing listOf with modelListOf.

[George Mount]

Or is it that the check/uncheck isn't working?

[wasyl]

Hey, thanks for answering. The problem isn’t adding to the list (although later on it would be, so thanks for the tip!).
The problem that I have is that even though I pass @Model instance to a composable functions, changes to that model don’t trigger the recomposition. Specifically in fun Item(item: ChildModel) I have onCheckedChange = { item.checked = it }. I’d expect that part of subtree to be recreated, while it isn’t

[wasyl]

Yep, check/uncheck exactly. Only saw that message after posting mine

[George Mount]

I think we typed at the same time 🙂

[George Mount]

I haven't seen this problem. I'm trying it locally.

[George Mount]

hmm... your example works for me. I'm working against tip-of-tree.

[George Mount]

I used:

@Composable
fun ListItem(text: @Composable() () -> Unit, trailing: @Composable() () -> Unit) {
    Row {
        text()
        trailing()
    }
}

[wasyl]

The code above is basically exactly what I’ve been trying, the only missing thing is

setContent {  MaterialTheme { App() } }

in Activity’s onCreate. I should be up to date too, a9891c6791.
My ListItem is androidx.ui.material.ListItemKt#ListItem

[wasyl]

Just tried again, copied the code verbatim + your ListItem. Clicking on checkboxes doesn’t change anything about the UI

[wasyl]

Can you please post the entire file (activity I assume?) complete with imports? I’ll try that locally too. Also maybe I have some weird issue with dependencies? I basically added all :ui:ui-* dependencies to the module

[wasyl]

I just checked again with --rerun-tasks to make sure it’s not some weird cache issue, and still doesn’t work 😕
I also synced the repo again, I’m on 8277cf7b6f

[romainguy]

And you’re using studiow or gradle studio right?

[wasyl]

Yep, ./gradlew studio

[wasyl]

I just created a separate module, no success. Do these dependencies seem right?

implementation(KOTLIN_COMPOSE_STDLIB)
~implementation(project(":ui:ui-android-view"))~
implementation project(":compose:compose-runtime")
implementation project(":ui:ui-core")
implementation project(":ui:ui-foundation")
~implementation project(":ui:ui-framework")~
implementation project(":ui:ui-animation")
implementation project(":ui:ui-layout")
implementation project(":ui:ui-text")
implementation project(':ui:ui-material')

[wasyl]

Here’s the entire thing for completeness: https://gist.github.com/lwasyl/6ba58e6bd3334a7fb5504f8d9bd95803. I have to log off for now, but I’d appreciate any help and suggestions

[wasyl]

Further experimentation:

@Composable
fun Item(item: ChildModel) {
    val stubState = +state { 0 }
    ListItem(
        text = { Text("${item.description} [${stubState.value} changes]") },
        trailing = { Checkbox(checked = item.checked, onCheckedChange = { }) },
        onClick = {
            item.checked = !item.checked
            stubState.value++
        }
    )
}

With this I get different texts when I click on the items, but the checked state still doesn’t change. But when I debug the calls to Text(... I can see that the model has an updated checked value

[wasyl]

Well, I know what the issue was. I was working within demos project, so I didn’t have compose plugin applied 😞

[wasyl]

I’ve added AndroidXUiPlugin plugin, kotlinPlugin project(path: ":compose:compose-compiler", configuration: "embeddablePlugin") dependency and useIR option to Kotlin plugin and it works. I had a feeling it’s something with dependencies, didn’t realize it would be that obvious

[Andrey Kulikov]

what probably happened for you is the compiler wasn't applied so no additional code was generated for @Model marked class and thus no recomposition happened

[wasyl]

Yep, sounds right. Sorry for the hassle, was pretty silly mistake

[Leland Richardson [G]]

This mistake isn’t actually that silly. I predict that this will happen to a LOT of people, myself included, until we figure out a way to trigger warnings or errors when we detect @Composable or @Model being compiled without the compose plugin. We don’t have an answer for this yet, but would like to figure it out soon. This is a big foot-gun and will cause people frustration in the near term 😕

[voddan]

@Leland Richardson [G] Mark @Model with @Deprecated(error) and then make your compiler plugin disable it 🤔

[Leland Richardson [G]]

Yeah, this is a pretty good idea. we thought about this, or using the @ExperimentalFeature flag. IIRC there were some issues with this, and the messages that would result in other versions of android studio/kotlin would be pretty hard to understand what to do, so we decided against it i guess

[Leland Richardson [G]]

when we figured out this was going to be a problem we didn’t have a ton of time left either. we will definitely try to have a more robust warning/plan here for future rollouts