Jetpack组合在视图模型中观察muableStateOf

问题描述

我需要更新用户配置文件开关

1. 视图模型

class ProfileViewModel : BaseViewModel() {

    var greet = mutableStateOf(user.pushSetting.greet)
    var message = mutableStateOf(user.pushSetting.message)
    var messageDetails = mutableStateOf(user.pushSetting.messageDetails)

    var follow = mutableStateOf(user.pushSetting)
    var like = mutableStateOf(user.pushSetting.like)
    var comment = mutableStateOf(user.pushSetting.comment)

    fun updateUser() {
        println("--")
    }
}

2.可组合

@Composable
fun SettingCard(viewModel: ProfileViewModel) {

    Lists {
        Section {
            TextRow(text = "手机号码") { }
            TextRow(text = "修改密码", line = false) { }
        }

        Section {
            SwitchRow(text = "新好友通知", checkedState = viewModel.greet)
            SwitchRow(text = "新消息通知", checkedState = viewModel.message)
            SwitchRow(text = "消息显示详细", line = false, checkedState = viewModel.messageDetails)
        }
    }
}

3.SwitchRow

@Composable
fun SwitchRow(text: String, line: Boolean = true, checkedState: MutableState<Boolean>) {

    ListItem(
        text = { Text(text) },
        trailing = {
            Switch(
                checked = checkedState.value,
                onCheckedChange = { checkedState.value = it },
                colors = SwitchDefaults.colors(checkedThumbColor = MaterialTheme.colors.primary)
            )
        }
    )
}

如何观察开关的变化并在ViewModel中调用updateUser()

我知道这是一种方法，但它并不理想。网络更新将在每次初始化时被调用。有没有更好的解决方案？

LaunchedEffect(viewModel.greet) {
     viewModel.updateUser()
}

推荐答案

此问题的最佳解决方案是将unidirectional flow与SwitchRow一起使用，@Codecameo建议使用lambda。

但如果要观察Viewmodel中的MuableState，则可以使用snapshotFlow%s作为

var greet: MutableState<Boolean> = mutableStateOf(user.pushSetting.greet)

init {
    snapshotFlow { greet.value }
        .onEach {
            updateUser()
        }
        .launchIn(viewModelScope)
        //...
}

这篇关于Jetpack组合在视图模型中观察muableStateOf的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！