使用mutableState＆＃x27;启动ViewModel的价值

发布于 2025-02-07 17:48:15 字数 1008 浏览 3 评论 0原文

我定义了一个 var Showallevent = mutableStateOf（false）在我的ViewModel中并想在 init {}我的ViewModel，但是使用时，给我这个错误： IllegalstateException：阅读在拍摄快照或尚未应用的快照中创建的状态 我如何在我的ViewModel`撰写的init中使用我的值

@HiltViewModel
class EventPageVM @Inject constructor(
private val repository: EventRepository,
private val noteRepository: NoteRepository
) : ViewModel() {

private val _eventsList = MutableStateFlow<List<Event>>(emptyList())
val eventsList = _eventsList.asStateFlow()
///
var showAllEvent = mutableStateOf(false)
var showPastEvent = mutableStateOf(true)


init {
    viewModelScope.launch(Dispatchers.IO) {
        val fromTo = Extra.getFromToNextMonth(CivilDate())
        val start= if (showPastEvent.value)null else fromTo[0]
        val end=if (showAllEvent.value)null else fromTo[1]
        repository.getEvents(start, end).distinctUntilChanged().collect { result ->
            _eventsList.value = result
        }
    }

}

原文

i defined a
var showAllEvent = mutableStateOf(false) in my viewmodel
and want to use it in
init {} of my viewmodel,
but when use, give me this error:
IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied
how can i use my value in init of my viewmodel` in jetpack compose

@HiltViewModel
class EventPageVM @Inject constructor(
private val repository: EventRepository,
private val noteRepository: NoteRepository
) : ViewModel() {

private val _eventsList = MutableStateFlow<List<Event>>(emptyList())
val eventsList = _eventsList.asStateFlow()
///
var showAllEvent = mutableStateOf(false)
var showPastEvent = mutableStateOf(true)


init {
    viewModelScope.launch(Dispatchers.IO) {
        val fromTo = Extra.getFromToNextMonth(CivilDate())
        val start= if (showPastEvent.value)null else fromTo[0]
        val end=if (showAllEvent.value)null else fromTo[1]
        repository.getEvents(start, end).distinctUntilChanged().collect { result ->
            _eventsList.value = result
        }
    }

}

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一百个冬季 2025-02-14 17:48:15

我遇到了同样的问题，并选择将初始化移至JetPack撰写项目中的。尽管在初始化块中初始化状态的方法起初似乎很有用，但在尝试运行仪器测试时，它变得很痛苦。

这是关于该主题的冗长写作： https：/ /Jetc.dev/slack/2022-05-16-mutating-state-viewmodel-constructor.html

回复收藏 0 原文

放我走吧 2025-02-14 17:48:15

我想使用mutableStateOf创建的状态应从UI线程中写入/读取。当前，您使用dispatcher.io，这意味着在背景线程中读取状态。尝试使用dispatcher.main在与状态一起工作的代码中的上下文：

init {
    viewModelScope.launch {
        val fromTo = Extra.getFromToNextMonth(CivilDate())
        val start = if (showPastEvent.value) null else fromTo[0]
        val end = if (showAllEvent.value) null else fromTo[1]
        repository.getEvents(start, end).distinctUntilChanged().collect { result ->
            _eventsList.value = result
        }
    }
}

viewmodelscope.launch by默认情况下使用dispatchers.main上下文。

另一种方法是在viewmodel和收集在撰写功能中。

I guess states created using mutableStateOf should be written/read from the UI thread. Currently you use Dispatchers.IO which means that the state is read in the background thread. Try to use Dispatchers.Main context in code where you work with the state:

init {
    viewModelScope.launch {
        val fromTo = Extra.getFromToNextMonth(CivilDate())
        val start = if (showPastEvent.value) null else fromTo[0]
        val end = if (showAllEvent.value) null else fromTo[1]
        repository.getEvents(start, end).distinctUntilChanged().collect { result ->
            _eventsList.value = result
        }
    }
}

viewModelScope.launch by default uses Dispatchers.Main context.

Another approach is to use Flows in the ViewModel and collect them in the Compose functions.

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