Compose Navigation with Parcelable arguments

NavControllerComposeUtils.kt

@file:Suppress("UnnecessaryVariable", "PackageDirectoryMismatch")

package androidx.navigation

import android.os.Bundle
import android.os.Parcelable
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember

fun NavController.navigate(
    route: String,
    navOptions: NavOptions? = null,
    navigatorExtras: Navigator.Extras? = null,
    args: List<Pair<String, Parcelable>>? = null,
) {
    if (args == null || args.isEmpty()) {
        navigate(route, navOptions, navigatorExtras)
        return
    }
    navigate(route, navOptions, navigatorExtras)
    val addedEntry: NavBackStackEntry = backQueue.last()
    val argumentBundle: Bundle = addedEntry.arguments ?: Bundle().also {
        addedEntry.arguments = it
    }
    args.forEach { (key, arg) ->
        argumentBundle.putParcelable(key, arg)
    }
}

inline fun <reified T : Parcelable> NavController.navigate(
    route: String,
    navOptions: NavOptions? = null,
    navigatorExtras: Navigator.Extras? = null,
    arg: T? = null,
) {
    if (arg == null) {
        navigate(route, navOptions, navigatorExtras)
        return
    }
    navigate(
        route = route,
        navOptions = navOptions,
        navigatorExtras = navigatorExtras,
        args = listOf(T::class.qualifiedName!! to arg),
    )
}

inline fun <reified T : Parcelable> NavController.navigate(
    route: String,
    navOptions: NavOptions? = null,
    navigatorExtras: Navigator.Extras? = null,
    arg: Pair<String, T>? = null,
) {
    if (arg == null) {
        navigate(route, navOptions, navigatorExtras)
        return
    }
    navigate(
        route = route,
        navOptions = navOptions,
        navigatorExtras = navigatorExtras,
        args = listOf(arg),
    )
}

fun NavBackStackEntry.requiredArguments(): Bundle = arguments ?: throw IllegalStateException("Arguments were expected, but none were provided!")

@Composable
inline fun <reified T : Parcelable> NavBackStackEntry.rememberRequiredArgument(
    key: String = T::class.qualifiedName!!,
): T = remember {
    requiredArguments().getParcelable<T>(key) ?: throw IllegalStateException("Expected argument with key: $key of type: ${T::class.qualifiedName!!}")
}

@Composable
inline fun <reified T : Parcelable> NavBackStackEntry.rememberArgument(
    key: String = T::class.qualifiedName!!,
): T? = remember {
    arguments?.getParcelable(key)
}

val NavBackStackEntry?.routeName: String?
    get() {
        if (this == null) return null
        val routeName: String? = destination.route?.substringBefore('/')
        return routeName
    }

NavigationWithParcelableExercise.kt

package com.example.navigation

import android.os.Parcelable
import androidx.compose.material.Scaffold
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.navigation.NavBackStackEntry
import androidx.navigation.NavHostController
import androidx.navigation.compose.NavHost
import androidx.navigation.compose.composable
import androidx.navigation.compose.currentBackStackEntryAsState
import androidx.navigation.compose.rememberNavController
import androidx.navigation.navigate
import androidx.navigation.rememberRequiredArgument
import androidx.navigation.routeName
import kotlinx.parcelize.Parcelize

@Parcelize
data class UserDetails(
    val firstName: String,
    val lastName: String,
    val emailAddress: String,
    val age: Int,
) : Parcelable

enum class Route {
    USER_DETAILS_FORM,
    USER_DETAILS_CONFIRM;

    companion object {
        fun from(navBackStackEntry: NavBackStackEntry?): Route? =
            navBackStackEntry.routeName?.let { routeName: String ->
                try {
                    valueOf(routeName)
                } catch (e: IllegalArgumentException) {
                    null
                }
            }
    }
}

@Composable
fun NavigationExample() {
    val navController: NavHostController = rememberNavController()
    // these 2 are optional, but useful for when you want to detect the current screen and possibly set the
    // route name in the topBar composable of the Scaffold.
    val currentBackStackEntry: NavBackStackEntry? by navController.currentBackStackEntryAsState()
    val currentRoute: Route? = remember(currentBackStackEntry?.id) { Route.from(currentBackStackEntry) }
    Scaffold(
        topBar = {
            // You can use the currentRoute here to add some title for each route
        }
    ) {
        NavHost(
            navController = navController,
            startDestination = Route.USER_DETAILS_FORM.name,
        ) {
            composable(Route.USER_DETAILS_FORM.name) {
                UserDetailsForm(
                    onReadyToReviewClicked = { userDetails: UserDetails ->
                        navController.navigate(
                            route = Route.USER_DETAILS_CONFIRM.name,
                            // passing the parcelable UserDetails as a nav arg
                            arg = userDetails,
                        )
                    }
                )
            }
            composable(Route.USER_DETAILS_CONFIRM.name) { navBackStackEntry: NavBackStackEntry ->
                // use the NavBackStackEntry parameter in the lambda to access the UserDetails nav arg
                // since it's a required (non optional) nav arg of this screen, use the rememberRequiredArgument() extension:
                val userDetails: UserDetails = navBackStackEntry.rememberRequiredArgument()
                UserDetailsConfirm(
                    userDetails = userDetails,
                    onConfirmUserDetailsClicked = {
                        // TODO: for example, POST the details to some endpoint
                    }
                )
            }
        }
    }
}

@Composable
fun UserDetailsForm(
    onReadyToReviewClicked: (userDetails: UserDetails) -> Unit,
    modifier: Modifier = Modifier,
) {
    // TODO: 1. add editable form UI fields, also some 'review' button
    // TODO: 2. store form data in mutable states for each field in the form
    // TODO: 3. call onReadyToReviewClicked in the 'review' button's onClick,
    //          with a UserDetails object (build it from the multiple mutable states that are populated by the form)

}

@Composable
fun UserDetailsConfirm(
    userDetails: UserDetails,
    onConfirmUserDetailsClicked: () -> Unit,
    modifier: Modifier = Modifier,
) {
    // TODO: 1. add stateless UI (as in UI they can't change like in UserDetailsForm) using the passed in UserDetails, including some 'confirm' button
    // TODO: 2. call onConfirmUserDetailsClicked in the 'confirm' button's onClick
}

I got these errors

• Cannot access 'backQueue': it is private in 'NavController'
• Val cannot be reassigned for (addedEntry.arguments = it)

Don't use it, it doesn't work anymore. I would suggest looking for an alternative to compose navigation from Google, it's not a good solution, there's better alternatives out there.

Personally I'm using Decompose for a compose multiplatform app, but if you don't use multiplatform, you could use something else.

Okay thanks bro I found another solution