List search inside viewModel issue in Jetpack Compose-CodePudding

I am trying to make a name search functionality in a Compose project. I have a list of DummyClient, which I am using as my data source on a view model. I am trying to search this list, so the updated result can be shown on a LazyColumn, which is not returning any error but providing unexpected results.

class ClientViewModel : ViewModel() {
    private var _clients = MutableLiveData(dummyClients)
    val clients: LiveData<List<DummyClient>>
        get() = _clients

    fun searchClients(name: String) {
        val foundClients: List<DummyClient?> = listOf(dummyClients.find {
            it.name.contains(name)
        })
        _clients.value === foundClients
    }
}

This ViewModel is passed to the ClientDirectoryScreen composable from the navigation, which displays a search bar and the client list on a LazyColumn:

val clientViewModel: ClientViewModel = ViewModel()
...
composable(Screen.Clients.route) {
    ClientDirectoryScreen(
        ...
        clientViewModel = clientViewModel
    )
}

@Composable
fun ClientDirectoryScreen(
    ...
    clientViewModel: ClientViewModel
) {
    val clients by clientViewModel.clients.observeAsState(listOf())
    val showSearchBar by clientViewModel.showSearchBar.observeAsState(false)

    if (clients.isNotEmpty()) {
        Column {

            // show the search bar on search icon click
            if (showSearchBar) ClientSearchCard(clientViewModel)

            LazyColumn(verticalArrangement = Arrangement.spacedBy(4.dp)) {
                items(clients) { client ->
                    ClientNameCard(client)
                }
            }
        }
    }
}

And the search bar invokes the search in the ViewModel, which doesn't reflect the search:

@Composable
fun ClientSearchCard(clientViewModel: ClientViewModel) {
    var searchText by remember { mutableStateOf("") }

    Column(
        modifier = Modifier
            .fillMaxWidth()
            .padding(16.dp)
    ) {
        TextField(
            value = searchText,
            onValueChange = {
                searchText = it
                clientViewModel.searchClients(searchText)
            },
            label = { Text("Search:") },
            modifier = Modifier.fillMaxWidth()
        )
    }
}

If I log the search result in the view model, the search doesn't provide the correct result. Also, I don't see any state change for the clients variable in ClientDirectoryScreen.

CodePudding user response：

find will return you only one element, and the result is optional, because collection may have none.

Instead you can use filter on the collection: it'll return all matching elements:

val foundClients = dummyClients.filter {
    it.name.contains(name)
}
_clients.value = foundClients