StateFlow未按预期收集

我正在做一个样本项目 fetchPosts 使用compose/clean体系结构 blog post :

存储库包含:

override fun getPosts(postId: Int): Flow<List<PostModel>>  = flow {
        val fromListDto = postMapper.fromListDto(postService.getPosts(postId).data)
        emit(fromListDto)
    }

给我 viewModel :

@HiltViewModel
class PostViewModel @Inject constructor(
    private val postUseCase: GetPostUseCase
) : ViewModel() {


    private val _uiState = MutableStateFlow(PostUiState.Loading)
    val uiState: StateFlow<PostUiState> = _uiState.asStateFlow()

    fun fetchPosts() {
        viewModelScope.launch {
            postUseCase.invoke(0)
                .asResult()
                .map { result ->
                    when (result) {
                        is Result.Success -> PostUiState.Success(result.data)
                        is Result.Loading -> PostUiState.Loading
                        is Result.Error -> PostUiState.Error
                    }
                }.stateIn(
                    scope = viewModelScope,
                    initialValue = PostUiState.Loading,
                    started = SharingStarted.WhileSubscribed(DEFAULT_TIMEOUT)
                ).collect()
            }

        }
}

这是我的视图部分屏幕:

@Composable
fun PostScreen(
    navController: NavController,
    modifier: Modifier = Modifier,
    viewModel: PostViewModel = hiltViewModel()
) {
    LaunchedEffect(Unit) {
        viewModel.fetchPosts()
    }

    val uiState: PostUiState by viewModel.uiState.collectAsState()

    LazyVerticalGrid(
        columns = GridCells.Adaptive(100.dp),
        horizontalArrangement = Arrangement.spacedBy(8.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp),
        contentPadding = PaddingValues(
            top = 16.dp,
            bottom = 16.dp
        )
    ) {


        when (val postState = uiState) {
            PostUiState.Error -> {
                item(span = { GridItemSpan(maxLineSpan) }) {
                    Text(
                        "Error fetching posts",
                        modifier = Modifier
                            .padding(horizontal = 16.dp)
                    )
                }
            }

            PostUiState.Loading -> {
                item(span = { GridItemSpan(maxLineSpan) }) {
                    //LoadingIndicator()
                    Text(
                        "Loading ...",
                        modifier = Modifier
                            .padding(horizontal = 16.dp)
                    )
                }
            }

            is PostUiState.Success -> {
                items(postState.posts) { movie ->
                    PostImage(movie)
                }

                item(span = { GridItemSpan(maxLineSpan) }) {
                    Spacer(Modifier.height(16.dp))
                }
            }
        }
    }
}

当我将我的viewModel更改为此(有效)时:

fun fetchPosts() {
        viewModelScope.launch {
            postUseCase
                .invoke(0)
                //.asResult()
                .collect { result ->
                    _uiState.value = GenreScreenUiState(PostUiState.Success(result))

                    }

                }

        }
    }