Api 响应未更新，导致第一次调用失败

Question

 var authViewModel: UserAuthViewModel = hiltViewModel()
    val userData by authViewModel.authUserData.collectAsState()

fun checkUserforEmnail(
    sharedViewModel: SharedViewModel,
    userData: AuthResponseModel?,
    authViewModel : UserAuthViewModel,
    navController: NavController,
    textUser: String
) {
    Log.d("TAG", "checkUserforEmnail: ${userData}")
    if (userData == null){
        authViewModel.getAuthUserDataEmail(textUser = textUser)
        Log.d("TAG", "checkUserforEmnail: ${userData}")
    }
    if(userData?.result?.user_exist == "USER_NOT_EXISTS"){
        navController.navigate(NavScreens.REGISTRATION.route)
    }
    else if(userData?.result?.user_exist == "ACCOUNT_EXISTS") {
        sharedViewModel.addUsername(userName = textUser)
        navController.navigate(NavScreens.LOGIN.route)
    }
    else if(userData?.result?.user_exist == "ACCOUNT_NOT_VERIFIED"){

    }

}

ViewModel

@HiltViewModel
class UserAuthViewModel @Inject constructor(private val repository: Repository) : ViewModel()  {

    val authUserData: StateFlow<AuthResponseModel?> get() = repository.authUserData

    fun getAuthUserData(textUser: String, countryCode:String){
        viewModelScope.launch {
            val result = repository.getAuthUserData(AuthUser(username = textUser, country_dial_code = countryCode))
        }
    }

    fun getAuthUserDataEmail(textUser: String) {
        viewModelScope.launch {
            val result = repository.getAuthUserData(AuthUser(username = textUser))
        }
    }
}

所以问题是我在单击“okk”时称此为有趣，所以在第一次单击时我将用户数据记录为空，但是当我再次单击它时，它会按预期获取数据，所以我认为正在发生的事情是因为响应花费了一点时间，这是正常时间，我的代码不等待响应，因此默认响应为空并使用它，但第二次它使用 userData 中的新数据，我看到了响应。所以我的问题是如何解决这个问题

Answer 1

如果我正确理解您的数据流，您将请求发送到

getAuthUserDataEmail

，忽略返回值，而是从

AuthResponseModel

收集

repository.authUserData

。这是一种容易出错的方法。

不要使用

StateFlow

并在

Composable

中执行业务逻辑，而是使用

repository.getAuthUserData

返回的值并在

UserAuthViewModel

中的同一协程中更新 UI 状态。可组合项应基于该 UI 状态进行导航。

示例

ViewModel

：

sealed class AuthState {
    object SignedOut : AuthState()
    object Exist : AuthState()
    object NotExist : AuthState()
    object NotVerified : AuthState()
}

@HiltViewModel
class UserAuthViewModel @Inject constructor(private val repository: Repository) : ViewModel()  {
    private val _authState = MutableStateFlow<AuthState>(AuthState.SignedOut)
    val authState: StateFlow<AuthState>
        get() = _authState

    fun getAuthUserDataEmail(textUser: String) {
        viewModelScope.launch {
            val userData = repository.getAuthUserData(AuthUser(username = textUser))
            // update UI state here
            if (userData?.result?.user_exist == "USER_NOT_EXISTS") {
                _authState.value = AuthState.NotExist
            }
            // rest of the logic
        }
    }
}

可组合：

val authState by authViewModel.authState.collectAsStateWithLifecycle()

LaunchedEffect(authState) {
    when (authState) {
        AuthState.Exist -> { navController.navigate(NavScreens.LOGIN.route) }
        AuthState.NotExist -> TODO()
        AuthState.NotVerified -> TODO()
        AuthState.SignedOut -> TODO()
    }
}