IssueTracker

Jetpack Compose component(s) used: androidxCompose = "1.3.0-rc01" androidxComposeCompiler = "1.3.2" androidxComposeMaterial3 = "1.0.0-alpha13" androidxComposeMaterial = "1.2.1"

Android Studio Build: Build #AI-222.4167.29.2221.9133400, built on October 4, 2022

Kotlin version: kotlin = "1.7.20"

Steps to Reproduce or Code Sample to Reproduce:

I struggle with a "Key" problem since I updated from androidx.compose "1.3.0-beta03" to "1.3.0-rc01".

I use LazyPagingItems for a LazyVerticalGrid and i add items like this in the LazyGridScope:

fun LazyGridScope.itemFeed(pagingData: Flow<PagingData<DangerItem>>){
val feedData = pagingData.collectAsLazyPagingItems()
items(feedData.itemCount,
        // to maximize the performance add a unique key
        // as fallback use index of element
        key = { index ->
            feedData[index]?.code ?: index
        },
        contentType = { idx ->
            if (feedData[idx] != null) 1 else 0
        }
    )

But since the library update, when I filter the content (so the paging items are updated in the flow), it throws an Exception. This exception wasn't thrown in the beta03 library version.

Because paging data is changing and elements become null while loading I can't supply a unique key, the App crashes. Is this a bug in the library or what exactly is the best practice when using LazyPagingItems that can change over time if you'd like to work with keys in the LazyGrid?

Stack trace (if applicable):

java.lang.IllegalArgumentException: Failed requirement. 
at androidx.compose.foundation.lazy.grid.LazyGridSpanLayoutProvider.getLineIndexOfItem--_Ze7BM(LazyGridSpanLayoutProvider.kt:174) 
at androidx.compose.foundation.lazy.grid.LazyGridItemPlacementAnimatorKt.lastIndexInPreviousLineBefore(LazyGridItemPlacementAnimator.kt:489)
at androidx.compose.foundation.lazy.grid.LazyGridItemPlacementAnimatorKt.access$lastIndexInPreviousLineBefore(LazyGridItemPlacementAnimator.kt:1)