Add type-safe navigation

[dturner]

Overview
Navigation 2.8.0 introduces type-safe APIs for the Navigation DSL. Instead of using strings for routes and argument names, you can define types which are verified at compile-time. This blog post explains more.

What have I done and why
Migrated the navigation code from strings to types. For example, here's the old navigation code for the topic feature:

const val TOPIC_ID_ARG = "topicId"
const val TOPIC_ROUTE = "topic_route"

fun NavController.navigateToTopic(topicId: String, navOptions: NavOptionsBuilder.() -> Unit = {}) {
    val encodedId = URLEncoder.encode(topicId, URL_CHARACTER_ENCODING)
    val newRoute = "$TOPIC_ROUTE/$encodedId"
    navigate(newRoute) {
        navOptions()
    }
}

fun NavGraphBuilder.topicScreen(
    showBackButton: Boolean,
    onBackClick: () -> Unit,
    onTopicClick: (String) -> Unit,
) {
    composable(
        route = "topic_route/{$TOPIC_ID_ARG}",
        arguments = listOf(
            navArgument(TOPIC_ID_ARG) { type = NavType.StringType },
        ),
    ) {
        TopicScreen(...)
    }
}

And here's the new type-safe code:

@Serializable data class Topic(val id: String)

fun NavController.navigateToTopic(topicId: String, navOptions: NavOptionsBuilder.() -> Unit = {}) {
    navigate(route = Topic(topicId)) {
        navOptions()
    }
}

fun NavGraphBuilder.topicScreen(
    showBackButton: Boolean,
    onBackClick: () -> Unit,
    onTopicClick: (String) -> Unit,
) {
    composable<Topic> {
        TopicScreen(...)
    }
}

Note that there's no need to URL encode the arguments because there's no danger of them being interpreted as placeholders (e.g. "{topicId}") in the route string (because there is no route string).

I have also updated the app manifest to allow deeplinks to be tested from the terminal. Example: adb shell am start -a android.intent.action.VIEW -d "https://www.nowinandroid.apps.samples.google.com/foryou/2" com.google.samples.apps.nowinandroid.demo.debug

[github-actions]

Combined test coverage report

Overall Project	40.34% -0.49%	🍏
Files changed	57.67%	❌

Module	Coverage
foryou	56.16% -3.2%	❌
bookmarks	51.21% -1.59%	❌
interests	49.95% -3.74%	❌
topic	47.33% -2.09%	❌
app	32% -0.09%	🍏

Files

Module	File	Coverage
foryou	ForYouNavigation.kt	0% -66.81%	❌
bookmarks	BookmarksNavigation.kt	0% -43.18%	❌
interests	InterestsViewModel.kt	100%	🍏
	InterestsNavigation.kt	48.81% -45.83%	❌
	InterestsScreen.kt	25.7% -0.09%	❌
topic	TopicViewModel.kt	73.38%	🍏
	TopicScreen.kt	49.85%	🍏
	TopicNavigation.kt	33.62% -31.9%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	92.15% -0.69%	🍏
	NiaAppState.kt	90.61% -1.04%	🍏
	NiaApp.kt	83.44%	🍏
	NiaNavHost.kt	81.03%	🍏

[github-actions]

Combined test coverage report

Overall Project	40.34% -0.49%	🍏
Files changed	55.61%	❌

Module	Coverage
foryou	56.16% -3.2%	❌
bookmarks	51.21% -1.59%	❌
interests	49.95% -3.69%	❌
topic	47.33% -2.09%	❌
app	32% -0.09%	🍏

Files

Module	File	Coverage
foryou	ForYouNavigation.kt	0% -66.81%	❌
bookmarks	BookmarksNavigation.kt	0% -43.18%	❌
interests	InterestsViewModel.kt	100%	🍏
	InterestsNavigation.kt	48.81% -45.24%	❌
	InterestsScreen.kt	25.7% -0.09%	❌
topic	TopicViewModel.kt	73.38%	🍏
	TopicScreen.kt	49.85%	🍏
	TopicNavigation.kt	33.62% -31.9%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	92.15% -0.69%	🍏
	NiaAppState.kt	90.61% -1.04%	🍏
	NiaApp.kt	83.44%	🍏
	NiaNavHost.kt	81.03%	🍏

[github-actions]

Combined test coverage report

Overall Project	40.37% -0.49%	🍏
Files changed	55.94%	❌

Module	Coverage
foryou	56.16% -3.2%	❌
bookmarks	51.21% -1.59%	❌
interests	49.95% -3.69%	❌
topic	47.33% -2.09%	❌
app	32.04% -0.09%	🍏

Files

Module	File	Coverage
foryou	ForYouNavigation.kt	0% -66.81%	❌
bookmarks	BookmarksNavigation.kt	0% -43.18%	❌
interests	InterestsViewModel.kt	100%	🍏
	InterestsNavigation.kt	48.81% -45.24%	❌
	InterestsScreen.kt	25.7% -0.09%	❌
topic	TopicViewModel.kt	73.38%	🍏
	TopicScreen.kt	49.85%	🍏
	TopicNavigation.kt	33.62% -31.9%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	92.15% -0.69%	🍏
	NiaAppState.kt	90.61% -1.04%	🍏
	NiaApp.kt	83.44%	🍏
	NiaNavHost.kt	81.61%	🍏

[github-actions]

Combined test coverage report

Overall Project	40.36% -0.49%	🍏
Files changed	58.1%	❌

Module	Coverage
foryou	56.16% -3.2%	❌
bookmarks	51.21% -1.59%	❌
interests	49.95% -3.69%	❌
topic	47.33% -2.09%	❌
app	32.1% -0.06%	🍏

Files

Module	File	Coverage
foryou	ForYouNavigation.kt	0% -66.81%	❌
bookmarks	BookmarksNavigation.kt	0% -43.18%	❌
interests	InterestsViewModel.kt	100%	🍏
	InterestsNavigation.kt	48.81% -45.24%	❌
	InterestsScreen.kt	25.7% -0.09%	❌
topic	TopicViewModel.kt	73.38%	🍏
	TopicScreen.kt	49.85%	🍏
	TopicNavigation.kt	33.62% -31.9%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	93.88% -0.28%	🍏
	NiaAppState.kt	90.61% -1.04%	🍏
	NiaApp.kt	83.44%	🍏
	NiaNavHost.kt	81.61%	🍏

[github-actions]

Combined test coverage report

Overall Project	41.48% -0.2%	🍏
Files changed	70.51%	🍏

Module	Coverage
foryou	60.17% -1.09%	❌
bookmarks	55.06% -1.25%	❌
interests	50.52% -1.63%	❌
topic	49.92% -0.7%	🍏
app	30.43% -0.05%	🍏

Files

Module	File	Coverage
foryou	ForYouScreen.kt	57.33%	🍏
	ForYouNavigation.kt	0% -58.02%	❌
bookmarks	BookmarksNavigation.kt	0% -41.18%	❌
interests	InterestsViewModel.kt	95.28% -3.94%	🍏
	InterestsNavigation.kt	29.27% -60.98%	❌
topic	TopicViewModel.kt	72.49%	🍏
	TopicScreen.kt	52.93%	🍏
	TopicNavigation.kt	14.29% -20.95%	❌
app	TopLevelDestination.kt	100%	🍏
	NiaAppState.kt	94.92% -0.35%	🍏
	InterestsListDetailScreen.kt	94.14% -0.11%	🍏
	Interests2PaneViewModel.kt	91.43% -8.57%	🍏
	NiaApp.kt	89.87%	🍏
	NiaNavHost.kt	83.53%	🍏

[github-actions]

Combined test coverage report

Overall Project	44.67% -0.21%	🍏
Files changed	70.12%	🍏

Module	Coverage
foryou	60.31% -0.79%	❌
bookmarks	54.03% -1.25%	❌
interests	50.35% -2.15%	❌
topic	49.92% -0.7%	🍏
app	48.47% -0.04%	🍏

Files

Module	File	Coverage
foryou	ForYouViewModel.kt	88.33%	🍏
	ForYouScreen.kt	57.33%	🍏
	ForYouNavigation.kt	0% -45.33%	❌
bookmarks	BookmarksNavigation.kt	0% -41.18%	❌
interests	InterestsViewModel.kt	94.7% -4.55%	🍏
	InterestsNavigation.kt	24% -68%	❌
topic	TopicViewModel.kt	72.49%	🍏
	TopicScreen.kt	52.93%	🍏
	TopicNavigation.kt	14.29% -20.95%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	98.34%	🍏
	NiaAppState.kt	94.79%	🍏
	Interests2PaneViewModel.kt	91.43% -8.57%	🍏
	NiaApp.kt	89.98%	🍏
	NiaNavHost.kt	83.2%	🍏

[alexvanyo]

Looks great!

[github-actions]

Combined test coverage report

Overall Project	42.34% -0.21%	🍏
Files changed	69.28%	🍏

Module	Coverage
bookmarks	52.45% -1.15%	❌
foryou	52.31% -0.75%	❌
app	48.16% -0.06%	🍏
interests	45.28% -1.93%	❌
topic	44.14% -0.73%	🍏

Files

Module	File	Coverage
bookmarks	BookmarksNavigation.kt	0% -35.9%	❌
foryou	ForYouViewModel.kt	88.33%	🍏
	ForYouScreen.kt	48.71%	🍏
	ForYouNavigation.kt	0% -44.71%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	93.9%	🍏
	Interests2PaneViewModel.kt	91.43% -8.57%	🍏
	NiaAppState.kt	90.53% -0.36%	🍏
	NiaApp.kt	86.51%	🍏
	NiaNavHost.kt	81.4%	🍏
interests	InterestsViewModel.kt	94.7% -4.55%	🍏
	InterestsNavigation.kt	24% -68%	❌
topic	TopicViewModel.kt	72.49%	🍏
	TopicScreen.kt	45.88%	🍏
	TopicNavigation.kt	13.39% -23.21%	❌

[Jaehwa-Noh]

Could you check this PR release mode onto the device or emulator? May the @Serializable Route be obfuscated, and makes runtime error. In this, you need to update a proguard rules.

[github-actions]

Combined test coverage report

Overall Project	42.31% -0.21%	🍏
Files changed	69.28%	🍏

Module	Coverage
bookmarks	52.45% -1.15%	❌
foryou	52.31% -0.75%	❌
app	48.16% -0.06%	🍏
interests	45.28% -1.93%	❌
topic	44.14% -0.73%	🍏

Files

Module	File	Coverage
bookmarks	BookmarksNavigation.kt	0% -35.9%	❌
foryou	ForYouViewModel.kt	88.33%	🍏
	ForYouScreen.kt	48.71%	🍏
	ForYouNavigation.kt	0% -44.71%	❌
app	TopLevelDestination.kt	100%	🍏
	InterestsListDetailScreen.kt	93.9%	🍏
	Interests2PaneViewModel.kt	91.43% -8.57%	🍏
	NiaAppState.kt	90.53% -0.36%	🍏
	NiaApp.kt	86.51%	🍏
	NiaNavHost.kt	81.4%	🍏
interests	InterestsViewModel.kt	94.7% -4.55%	🍏
	InterestsNavigation.kt	24% -68%	❌
topic	TopicViewModel.kt	72.49%	🍏
	TopicScreen.kt	45.88%	🍏
	TopicNavigation.kt	13.39% -23.21%	❌