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# compose

[Slackbot]

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[Aaron Waller]

in my ViewModel:

private val _itemList = mutableStateListOf<Post>()
val itemList: List<Post> = _itemList

fun likePost(newPost: Post){
        val index = _itemList.indexOf(newPost)
        _itemList[index] = _itemList[index].copy(isLiked = true)
}

Here my Post data class:

data class Post(
    val id: Int,
    val name: String, 
    val isLiked: Boolean = false,
)

And here my Composable:

val postList = viewModel.itemList

LazyRow(content = {

    items(postList.size) { i ->
        val postItem = postList[i]
        PostItem(
            name = postItem.name,
            isLiked = postItem.isLiked,
            likePost = { viewModel.likePost(postItem)}
        )

    }
})

The change does not update in the UI instantly, I first have to scroll the updated item out of the screen so it recomposes or switch to another Screen and go back to see the change.

[Aaron Waller]

I also posted the question on Stack: https://stackoverflow.com/questions/72951327/mutablestatelistof-change-not-reflecting-in-ui-jetpack-compose

[Vahalaru]

The problem is in your viewmodel. You need to do a deep copy first then set the isLiked.
fun likePost(newPost: Post){
val index = _itemList.indexOf(newPost)
_itemList[index] = _itemList[index].copy()
_itemList[index].isLiked = true
}