如何在JetPack组成的类型安全导航中设置导航参数的默认值？

Question

i最近开始使用JetPack Compacts中的新型安全导航功能。以前，我可以通过这样的导航参数传递默认值：

class WalletGiftDetailLandingArgs(
    private val savedStateHandle: SavedStateHandle,
) {
    val giftRefId: String
        get() = savedStateHandle[KEY_GIFT_REF_ID] ?: ""

    val isFromRedemptionReminderNotification: Boolean
        get() = savedStateHandle[KEY_IS_FROM_REDEMPTION_REMINDER_NOTIFICATION] ?: false
}

object WalletGiftDetailDestination : NavigableDestination(
    route = "$ROUTE/{$KEY_GIFT_TYPE}/{$KEY_GIFT_REF_ID}/{$KEY_IS_FROM_REDEMPTION_REMINDER_NOTIFICATION}",
)

fun NavGraphBuilder.walletGiftDetailScreen(
    giftRefId: String = "",
    isFromRedemptionReminderNotification: Boolean,
    onClickBack: () -> Unit,
    onRemoveFromWalletSuccess: () -> Unit,
    onRedirectToReceivedGiftsScreen: () -> Unit,
) {
    composable(
        route = WalletGiftDetailDestination.route,
        arguments = listOf(
            navArgument(KEY_GIFT_REF_ID) {
                type = NavType.StringType
                defaultValue = giftRefId
            },
            navArgument(KEY_IS_FROM_REDEMPTION_REMINDER_NOTIFICATION) {
                type = NavType.BoolType
                defaultValue = isFromRedemptionReminderNotification
            }
        )
    ) {
        WalletGiftDetailScreenRoute(
            onClickBack = onClickBack,
            onRemoveFromWalletSuccess = onRemoveFromWalletSuccess,
            onRedirectToReceivedGiftsScreen = onRedirectToReceivedGiftsScreen
        )
    }
}

在ViewModel中，我可以安全地从SavedStateHandle中检索值。

在新的类型安全导航中，我尝试了以下操作：

@Serializable
class WalletGiftDetailLandingArgs(
    val giftRefId: String,
    val isFromRedemptionReminderNotification: Boolean,
)

fun NavGraphBuilder.walletGiftDetailScreen(
    giftRefId: String = "",
    isFromRedemptionReminderNotification: Boolean,
    onClickBack: () -> Unit,
    onRemoveFromWalletSuccess: () -> Unit,
    onRedirectToReceivedGiftsScreen: () -> Unit,
) {
    composable<WalletGiftDetailLandingArgs> {
        WalletGiftDetailScreenRoute(
            onClickBack = onClickBack,
            onRemoveFromWalletSuccess = onRemoveFromWalletSuccess,
            onRedirectToReceivedGiftsScreen = onRedirectToReceivedGiftsScreen
        )
    }
}

wo，我不知道如何在新的类型安全导航设置中传递参数的默认值。 aadditional难度：

如果我尝试通过将默认值直接传递到组合性来处理默认值，我会遇到另一个问题：屏幕重编组件。每个重组再次调用函数，这可能导致ViewModel重新运行逻辑（例如传递给它的获取或处理值）。这效率低下，可能导致意外副作用。

有一种适当的方法来定义类型安全导航系统中的默认参数，以避免这些问题，或者是否有建议的解决方法？

任何指导都将不胜感激！

任何指导都将不胜感激！

我在代码中添加了评论，以更好地理解。让我知道您是否有任何疑问。

// Destination Route
@Serializable
data class WalletGiftDetailDestination(
    // argument
    val giftRefId: String = "", // default value
    // argument
    val isFromRedemptionReminderNotification: Boolean = false, // default value
)

fun NavGraphBuilder.walletGiftDetailScreen(
    // don't pass arguments here
//    giftRefId: String = "",
//    isFromRedemptionReminderNotification: Boolean,
    onClickBack: () -> Unit,
    onRemoveFromWalletSuccess: () -> Unit,
    onRedirectToReceivedGiftsScreen: () -> Unit,
) {
    composable<WalletGiftDetailDestination> { backStackEntry ->
        // get arguments from backStackEntry if you want to pass them to screen composable instead of getting them in viewModel
        val destination: WalletGiftDetailDestination = backStackEntry.toRoute()
        WalletGiftDetailScreenRoute(
            giftRefId = destination.giftRefId,
            isFromRedemptionReminderNotification = destination.isFromRedemptionReminderNotification,
            onClickBack = onClickBack,
            onRemoveFromWalletSuccess = onRemoveFromWalletSuccess,
            onRedirectToReceivedGiftsScreen = onRedirectToReceivedGiftsScreen
        )
    }
}

/////////////////////////////////////////

// can be used to get arguments in viewModel but seems boilerplate code to me with type-safe navigation
class WalletGiftDetailLandingArgs(
    private val savedStateHandle: SavedStateHandle,
) {
    val giftRefId: String
        get() = savedStateHandle.toRoute<WalletGiftDetailDestination>().giftRefId

    val isFromRedemptionReminderNotification: Boolean
        get() = savedStateHandle.toRoute<WalletGiftDetailDestination>().isFromRedemptionReminderNotification
}

class WalletGiftDetailViewModel(
    savedStateHandle: SavedStateHandle,
) : ViewModel() {
    // get arguments from savedStateHandle in viewModel using WalletGiftDetailLandingArgs helper class
    private val args = WalletGiftDetailLandingArgs(savedStateHandle)

    private val betterArgs = savedStateHandle.toRoute<WalletGiftDetailDestination>()

    init {
        println(args.giftRefId)
        println(args.isFromRedemptionReminderNotification)

        println(betterArgs.giftRefId)
        println(betterArgs.isFromRedemptionReminderNotification)
    }
}

/////////////////////////////////////////

navController.navigate(
    WalletGiftDetailDestination(
        // pass arguments here if needed otherwise default values will be used
    )
)