uno-navigation

name	uno-navigation
description	Uno Platform Navigation Extensions: region-based navigation, route registration, programmatic and XAML navigation, data passing, qualifiers, NavigationView, TabBar, responsive shells, dialogs, and troubleshooting. Use when: (1) Setting up navigation in an Uno Platform app, (2) Defining routes with ViewMap/DataViewMap/RouteMap, (3) Implementing NavigationView or TabBar navigation, (4) Passing data between pages, (5) Showing dialogs or flyouts via navigation, (6) Debugging blank pages or broken navigation. Do NOT use for: MVUX state management (see mvux), general XAML layout (see winui-xaml), new project scaffolding (see uno-platform-agent).
license	MIT
metadata	{"version":"1.0.0","author":"Uno Platform","category":"uno-platform-navigation","tags":["navigation","regions","routing","tabbar","navigationview","uno-platform"]}

Uno Platform Navigation Extensions

Region-based navigation system for Uno Platform apps. Navigation controls (NavigationView, TabBar) are linked to content areas via regions. Routes map views to ViewModels. Navigation can be triggered from XAML declaratively or from code programmatically.

Quick Reference

1. Add Navigation;Toolkit to <UnoFeatures> and call .UseToolkitNavigation() in App.xaml.cs
2. Register ALL views with ViewMap/DataViewMap in RegisterRoutes — missing maps cause reflection fallback warnings
3. NEVER put Region.Attached="True" inside Shell.xaml or ExtendedSplashScreen — the host isn't ready yet
4. NavigationView MUST use Frame (not Visibility navigator) for its content — Visibility inside NavigationView renders blank
5. TabBar/NavigationView items use uen:Region.Name to link to content areas with matching names
6. The root Grid containing both the navigation control and content MUST have uen:Region.Attached="True"
7. Qualifiers: - = back, -/ = clear back stack, ! = dialog; XAML prefix or C# Qualifiers.*
8. Data is injected into target ViewModel via constructor parameter — requires DataViewMap registration
9. Use ./ prefix in Navigation.Request for nested region navigation (ContentControl, Panel)
10. Set IsDefault: true on one nested route to auto-navigate on load — missing this causes blank content

Key Concepts

Navigation Control Categories

Category	Control	Behavior
Stack-based	Frame	Forward/backward with back stack
Visibility	Grid/Panel	Toggles child Visibility (no back stack)
Content	ContentControl	Replaces Content (no back stack)
Selection	NavigationView, TabBar	Selects item by Region.Name
Prompt	ContentDialog, MessageDialog, Flyout, Popup	Opens/closes via dialog qualifier

Region System

Regions link navigation controls to content areas using three attached properties:

xmlns:uen="using:Uno.Extensions.Navigation.UI"

<!-- Region.Attached: enables region-based navigation on a container -->
<Grid uen:Region.Attached="True">

    <!-- Region.Navigator: defines how content is displayed -->
    <Grid uen:Region.Attached="True" uen:Region.Navigator="Visibility">

        <!-- Region.Name: identifies which route this area represents -->
        <Grid uen:Region.Name="Home" Visibility="Collapsed">
            <TextBlock Text="Home" />
        </Grid>
    </Grid>

    <utu:TabBar uen:Region.Attached="True">
        <utu:TabBarItem uen:Region.Name="Home" Content="Home" />
    </utu:TabBar>
</Grid>

Route Registration

private static void RegisterRoutes(IViewRegistry views, IRouteRegistry routes)
{
    views.Register(
        new ViewMap(ViewModel: typeof(ShellViewModel)),
        new ViewMap<MainPage, MainViewModel>(),
        new ViewMap<ProductsPage, ProductsViewModel>(),
        new DataViewMap<DetailPage, DetailViewModel, Product>()
    );

    routes.Register(
        new RouteMap("", View: views.FindByViewModel<ShellViewModel>(),
            Nested:
            [
                new RouteMap("Main", View: views.FindByViewModel<MainViewModel>(), IsDefault: true,
                    Nested:
                    [
                        new RouteMap("Products", View: views.FindByViewModel<ProductsViewModel>(), IsDefault: true),
                        new RouteMap("Detail", View: views.FindByViewModel<DetailViewModel>())
                    ])
            ])
    );
}

Critical Patterns

NavigationView with Frame (Correct Shell Pattern)

<!-- CORRECT: Frame inside NavigationView for page navigation -->
<NavigationView uen:Region.Attached="True">
    <NavigationView.MenuItems>
        <NavigationViewItem Content="Products" uen:Region.Name="Products" />
        <NavigationViewItem Content="Settings" uen:Region.Name="Settings" />
    </NavigationView.MenuItems>
    <Frame uen:Region.Attached="True" />
</NavigationView>

<!-- WRONG: Visibility navigator inside NavigationView — renders blank -->
<NavigationView uen:Region.Attached="True">
    <NavigationView.MenuItems>
        <NavigationViewItem Content="Products" uen:Region.Name="Products" />
    </NavigationView.MenuItems>
    <Grid uen:Region.Attached="True" uen:Region.Navigator="Visibility">
        <Grid uen:Region.Name="Products" Visibility="Collapsed" />
    </Grid>
</NavigationView>

TabBar with Visibility Navigator

<!-- CORRECT: TabBar uses Visibility navigator for lightweight content switching -->
<Grid uen:Region.Attached="True">
    <Grid uen:Region.Attached="True" uen:Region.Navigator="Visibility">
        <Grid uen:Region.Name="Home" Visibility="Collapsed">
            <TextBlock Text="Home" />
        </Grid>
        <Grid uen:Region.Name="Search" Visibility="Collapsed">
            <TextBlock Text="Search" />
        </Grid>
    </Grid>
    <utu:TabBar uen:Region.Attached="True">
        <utu:TabBarItem uen:Region.Name="Home" />
        <utu:TabBarItem uen:Region.Name="Search" />
    </utu:TabBar>
</Grid>

XAML Declarative Navigation

<!-- Navigate forward -->
<Button Content="Details" uen:Navigation.Request="Detail" />

<!-- Navigate back -->
<Button Content="Back" uen:Navigation.Request="-" />

<!-- Clear back stack -->
<Button Content="Logout" uen:Navigation.Request="-/Login" />

<!-- Open dialog -->
<Button Content="Filter" uen:Navigation.Request="!Filter" />

<!-- ListView: selected item auto-passed as data -->
<ListView ItemsSource="{Binding Products}" uen:Navigation.Request="Detail" />

Programmatic Navigation

// Get navigator
var nav = this.Navigator(); // from code-behind
// Or inject: public MyViewModel(INavigator navigator)

// By ViewModel type
await nav.NavigateViewModelAsync<DetailViewModel>(this);

// By route name
await nav.NavigateRouteAsync(this, "Detail");

// With data
await nav.NavigateDataAsync(this, myProduct);

// Back
await nav.NavigateBackAsync(this);

// Back with result
await nav.NavigateBackWithResultAsync(this, data: selectedItem);

// Clear back stack
await nav.NavigateViewModelAsync<HomeViewModel>(this, qualifier: Qualifiers.ClearBackStack);

Common Mistakes

Setup:

• Missing UseToolkitNavigation() in App.xaml.cs — TabBar/NavigationView regions silently fail
• Missing Navigation;Toolkit in <UnoFeatures> — navigation extensions not available
• Region.Attached="True" inside Shell.xaml/ExtendedSplashScreen — host not ready, causes initialization errors
• NavigationView/TabBar defined in ShellView instead of MainPage — regions not functional

Regions:

• Root Grid missing uen:Region.Attached="True" — TabBar/NavigationView items don't switch content
• Region.Name mismatch between navigation item and content area — content doesn't display
• Content regions not initially set to Visibility="Collapsed" — all content visible at once
• Using Visibility navigator inside NavigationView — renders blank (must use Frame)

Routes:

• Missing ViewMap/DataViewMap registration — output window shows reflection fallback warning
• Missing IsDefault: true on a nested route — app launches to blank content area
• Route names conflicting with control names (List, Grid, Page, Content, Navigation) — resolves to wrong type
• Tab/menu routes not nested under parent page route — entire page replaces instead of just content area
• Route name using suffixes like Page, Model, ViewModel, Service — confuses the route resolver

Data passing:

• ViewModel doesn't accept data type as constructor parameter — data silently dropped
• Missing DataViewMap registration for the data type — navigation doesn't know which view to show
• Using Navigation.Data without Navigation.Request — data not sent

Navigation:

• Missing ./ prefix for ContentControl/Panel nested navigation — navigates at wrong level
• Forgetting await on navigation calls — race conditions or swallowed errors

Related Skills

Skill	Use instead when...
mvux	Implementing reactive data flow with feeds/states (not navigation)
uno-platform-agent	Creating a new Uno Platform project from scratch
wpf-to-uno-migration	Migrating WPF navigation patterns (Windows/dialogs → Pages/ContentDialogs)
uno-toolkit	Using TabBar/NavigationBar control features beyond navigation regions
winui-xaml	General XAML layout and binding (not navigation-specific)
uno-extensions-services	Configuring DI, auth, HTTP (not navigation-specific)

Detailed References

Read the reference file matching your current task:

• references/01-setup-host-configuration.md — Read when setting up navigation in a new project, configuring the host builder, or understanding the region system
• references/02-routes-viewmaps.md — Read when defining ViewMap, DataViewMap, ResultDataViewMap, RouteMap, or configuring nested routes
• references/03-programmatic-navigation.md — Read when navigating from code-behind or ViewModels, or using XAML declarative navigation
• references/04-data-and-results.md — Read when passing data between pages, implementing round-trip data, or using qualifiers
• references/05-navigation-controls.md — Read when implementing NavigationView, TabBar, ContentControl, or Panel/Visibility navigation
• references/06-responsive-shells.md — Read when building adaptive shells that switch between TabBar (mobile) and NavigationView (desktop)
• references/07-dialogs-flyouts.md — Read when showing dialogs, flyouts, message dialogs, or ContentDialogs via navigation

Docs Fallback

If the encoded knowledge above may be outdated, use MCP to fetch the latest:

uno_platform_docs_search("Uno Navigation overview regions setup")
uno_platform_docs_search("Uno Navigation routes ViewMap DataViewMap RouteMap")
uno_platform_docs_search("Uno Navigation INavigator programmatic code")
uno_platform_docs_search("Uno Navigation XAML attached properties Request Data")
uno_platform_docs_search("Uno Navigation qualifiers ClearBackStack dialog")
uno_platform_docs_search("Uno NavigationView region TabBar region")
uno_platform_docs_search("Uno Navigation responsive shell TabBar NavigationView")
uno_platform_docs_search("Uno Navigation dialog flyout ContentDialog MessageDialog")