Mi LazyColumn no se está recomponiendo pero el valor se está actualizando.

Si me desplazo hacia abajo en la lista y retrocedo hacia arriba, veo los valores correctos para la interfaz de usuario

Actividad principal

 class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { MyTheme { MyApp() } } } } // Start building your app here! @Composable fun MyApp(vm: PuppyListViewModel = viewModel()) { val puppers by vm.pups.collectAsState(emptyList()) Surface(color = MaterialTheme.colors.background) { Column { Toolbar() LazyColumn { items(puppers) { pup -> PuppyUI(pup, vm::seeDetails, vm::togglePuppyAdoption) } } } } }

El modelo de vista

 class PuppyListViewModel : ViewModel() { val pups = PuppyRepo.getPuppies().onEach { println("FlowEmitted: $it") } fun togglePuppyAdoption(puppy: Puppy) = viewModelScope.launch { PuppyRepo.toggleAdoption(puppy.id) } fun seeDetails(puppy: Puppy) { println("seeDetails $puppy") } }

El modelo

 internal var IDS = 0L data class Puppy ( val name: String, val tagline: String = "", val race: String, @DrawableRes val image: Int, var adopted: Boolean = false, val id: Long = ++IDS, )

el repositorio

 object PuppyRepo { private val changeFlow = MutableStateFlow(0) private val pups: List<Puppy> private val puppyImages = listOf( R.drawable._1, R.drawable._2, R.drawable._3, R.drawable._4, R.drawable._5, R.drawable._6, R.drawable._7, R.drawable._8, R.drawable._9, R.drawable._10, R.drawable._11, R.drawable._12, R.drawable._13, R.drawable._14, R.drawable._15, R.drawable._16, R.drawable._17, R.drawable._18, R.drawable._19, ) private val puppyNames = listOf( "Gordie", "Alice", "Belle", "Olivia", "Bubba", "Pandora", "Bailey", "Nala", "Rosco", "Butch", "Matilda", "Molly", "Piper", "Kelsey", "Rufus", "Duke", "Ozzy" ) private val puppyTags = listOf( "doggo", "doge", "special dogo", "wrinkler", "corgo", "shoob", "puggo", "pupper", "small dogo", "big ol dogo", "woofer", "floofer", "yapper", "pupper", "good-boye", "grizlord", "snip-snap dogo" ) private val puppyBreeds = listOf( "Labrador Retriever", "German Shepard", "Golden Retriever", "French Bulldog", "Bulldog", "Beagle", "Poodle", "Rottweiler", "German Shorthaired Pointer", "Yorkshire Terrier", "Boxer" ) init { pups = puppyImages.map { image -> val name = puppyNames.random() val tagline = puppyTags.random() val breed = puppyBreeds.random() Puppy(name, tagline, breed, image) } } @OptIn(ExperimentalCoroutinesApi::class) fun getPuppies() = changeFlow.flatMapLatest { flowOf(pups) } fun getPuppy(puppyId: Long) = flow { emit(pups.find { it.id == puppyId }) } suspend fun toggleAdoption(puppyId: Long): Boolean { val found = getPuppy(puppyId).first()?.toggleAdoption()?.let { true } ?: false if (found) { // Trigger a new emission for those that are consuming a Flow from getPuppies changeFlow.value = changeFlow.value + 1 } return found } private fun Puppy.toggleAdoption() { adopted = !adopted } }

Los cachorros de Flow están produciendo valores actualizados como se puede ver en mi logcat

He puesto declaraciones de impresión en mis componibles y no se vuelven a componer después de que el flujo emite un nuevo valor.

Editar.

Parece que Compose compara las referencias de los objetos y, dado que no cambiaron, la recomposición no ocurrió incluso si los flujos emitían nuevos valores (¿un error en Compose quizás?)

Cambió la funcionalidad de toggle para volver a crear las instancias de los elementos de la lista como la siguiente y ahora está funcionando.

Nota: he hecho que Puppy.adopted un val en lugar de var

 suspend fun toggleAdoption(puppyId: Long): Boolean { var found = false pups = pups.map { val isThePuppy = it.id == puppyId found = found || isThePuppy if(isThePuppy) it.copy(adopted = !it.adopted) else it.copy() } if (found) { // Trigger a new emission for those that are consuming a Flow from getPuppies changeFlow.value = changeFlow.value + 1 } return found }