maui-shell-navigation
Guide for implementing Shell-based navigation in .NET MAUI apps. Covers AppShell setup, visual hierarchy (FlyoutItem, TabBar, Tab, ShellContent), URI-based navigation with GoToAsync, route registration, query parameters, back navigation, flyout and tab configuration, navigation e
Install
npx skills add https://github.com/dotnet/skills/tree/main/plugins/dotnet-maui/skills/maui-shell-navigation
claude plugin marketplace add https://llmmart.ai/marketplace.json && claude plugin install dotnet-skills@llmmart
git clone https://github.com/dotnet/skills.git
The skills CLI installs just this skill, for any of its supported agents. Claude Code installs the whole dotnet/skills collection as a plugin from our marketplace. Git is the plain clone.
Skill manifest
.NET MAUI Shell Navigation
Implement page navigation in .NET MAUI apps using Shell. Shell provides URI-based navigation, a flyout menu, tab bars, and a four-level visual hierarchy — all configured declaratively in XAML.
When to Use
- Setting up top-level app navigation with tabs or a flyout menu
- Navigating between pages programmatically with
GoToAsync - Passing data between pages via query parameters or object parameters
- Registering detail-page routes for push navigation
- Guarding navigation with confirmation dialogs (e.g., unsaved changes)
- Customizing back button behavior per page
When Not to Use
- Deep linking from external URLs or app links — see .NET MAUI deep linking docs
- Data binding on navigation target pages — use
maui-data-binding - Dependency injection for pages and view models — use
maui-dependency-injection - Apps using
NavigationPagewithout Shell (different navigation API)
Inputs
- A .NET MAUI project with
AppShell.xamlas the root shell - Pages (
ContentPage) to navigate between - Route names for detail pages not in the visual hierarchy
Rules That Change the Answer
These are the Shell-specific decisions that are easy to get wrong. Apply them whenever they are relevant to what the user asked.
| Situation | Do this | Not this |
|---|---|---|
Declaring pages in AppShell.xaml |
With xmlns:views="clr-namespace:MyApp.Views" declared: <ShellContent ContentTemplate="{DataTemplate views:MyPage}" /> — the page is created on first navigation |
<ShellContent><views:MyPage /></ShellContent>, which constructs every page at startup |
| Navigating to a page not in the visual hierarchy | Routing.RegisterRoute("details", typeof(DetailsPage)) first |
Calling GoToAsync("details") unregistered — it throws at runtime |
| Receiving navigation parameters | Implement IQueryAttributable on the ViewModel |
Implementing it on the Page, which splits state from the BindingContext |
| Passing a whole object | ShellNavigationQueryParameters |
Serialising the object into the query string |
Any GoToAsync call |
await it |
Fire-and-forget — exceptions are swallowed and navigation races |
| Confirming before back navigation | ShellNavigatingEventArgs.GetDeferral() … deferral.Complete() |
Blocking synchronously on the dialog task |
| Detecting back navigation | Check e.Source == ShellNavigationSource.Pop |
Assuming every navigation is a back action |
Do not propose NavigationPage / PushAsync solutions for a Shell app, and do
not restructure a working AppShell hierarchy unless the user asked.
Answer narrowly, but completely. Staying on topic does not mean being terse. When
you show a navigation change, include the pieces needed to run it: the AppShell.xaml
markup and the Routing.RegisterRoute call, or the GoToAsync call and the
receiving IQueryAttributable / [QueryProperty] code. Where two approaches are both
valid (query string vs ShellNavigationQueryParameters), show both and say when each
fits — a single snippet the user still has to complete is a worse answer.
Shell Visual Hierarchy
Shell uses a four-level hierarchy. Each level wraps the one below it:
Shell
├── FlyoutItem / TabBar (top-level grouping)
│ ├── Tab (bottom-tab grouping)
│ │ ├── ShellContent (page slot → ContentPage)
│ │ └── ShellContent (multiple = top tabs)
│ └── Tab
└── FlyoutItem / TabBar
- FlyoutItem — appears in the flyout menu; contains
Tabchildren - TabBar — bottom tab bar with no flyout entry
- Tab — groups
ShellContent; multiple children produce top tabs - ShellContent — each points to a
ContentPage
Implicit Conversion
You can omit intermediate wrappers. Shell auto-wraps:
| You write | Shell creates |
|---|---|
ShellContent only |
FlyoutItem > Tab > ShellContent |
Tab only |
FlyoutItem > Tab |
ShellContent in TabBar |
TabBar > Tab > ShellContent |
Workflow: Set Up AppShell
- Define
AppShell.xamlinheriting fromShell - Add
FlyoutItemorTabBarelements for top-level navigation - Add
Tabelements for bottom tabs; nest multipleShellContentfor top tabs - Always use
ContentTemplatewithDataTemplateso pages load on demand - Give every
ShellContentan explicitRoute(see below) - Register detail-page routes in the
AppShellconstructor
Set
Route=on everyShellContent. If you omit it, MAUI auto-generates a name from a shared counter —Routing.csproducesD_FAULT_{TypeName}{n}. A real shell with three unnamedShellContentelements yields routes likeD_FAULT_ShellContent2andD_FAULT_ShellContent5: the numbers are not sequential, they depend on how many Shell elements were constructed first, and they shift when you reorder or add pages. You cannot write a stable absolute route (//dashboard) or deep link against that. An explicitRoute="dashboard"is stable forever.
<Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:views="clr-namespace:MyApp.Views"
x:Class="MyApp.AppShell"
FlyoutBehavior="Flyout">
<FlyoutItem Title="Animals" Icon="animals.png">
<Tab Title="Cats">
<ShellContent Title="Domestic" Route="domesticcats"
ContentTemplate="{DataTemplate views:DomesticCatsPage}" />
<ShellContent Title="Wild" Route="wildcats"
ContentTemplate="{DataTemplate views:WildCatsPage}" />
</Tab>
<Tab Title="Dogs" Icon="dogs.png">
<ShellContent Route="dogs" ContentTemplate="{DataTemplate views:DogsPage}" />
</Tab>
</FlyoutItem>
<TabBar>
<ShellContent Title="Home" Icon="home.png" Route="home"
ContentTemplate="{DataTemplate views:HomePage}" />
<ShellContent Title="Settings" Icon="settings.png" Route="settings"
ContentTemplate="{DataTemplate views:SettingsPage}" />
</TabBar>
</Shell>
// AppShell.xaml.cs
public partial class AppShell : Shell
{
public AppShell()
{
InitializeComponent();
Routing.RegisterRoute("animaldetails", typeof(AnimalDetailsPage));
Routing.RegisterRoute("editanimal", typeof(EditAnimalPage));
}
}
Workflow: Navigate with GoToAsync
All programmatic navigation uses Shell.Current.GoToAsync. Always await the call.
Route Prefixes
| Prefix | Meaning |
|---|---|
// |
Absolute route from Shell root |
| (none) | Relative; pushes onto the current nav stack |
.. |
Go back one level |
../ |
Go back then navigate forward |
Navigation Examples
// 1. Absolute — switch to a specific hierarchy location
await Shell.Current.GoToAsync("//animals/cats/domestic");
// 2. Relative — push a registered detail page
await Shell.Current.GoToAsync("animaldetails");
// 3. With query string parameters
await Shell.Current.GoToAsync($"animaldetails?id={animal.Id}");
// 4. Go back one page
await Shell.Current.GoToAsync("..");
// 5. Go back two pages
await Shell.Current.GoToAsync("../..");
// 6. Go back one page, then push a different page
await Shell.Current.GoToAsync("../editanimal");
Workflow: Pass Data Between Pages
Option 1: IQueryAttributable (Preferred)
Implement on ViewModels to receive all parameters in one call:
public class AnimalDetailsViewModel : ObservableObject, IQueryAttributable
{
public void ApplyQueryAttributes(IDictionary<string, object> query)
{
if (query.TryGetValue("id", out var id))
AnimalId = id.ToString();
}
}
Option 2: QueryProperty Attribute
Apply on the ViewModel class (or the page, if it genuinely owns the state).
Prefer IQueryAttributable on the ViewModel — it keeps navigation state with the
BindingContext and handles multiple parameters in one call:
[QueryProperty(nameof(AnimalId), "id")]
public partial class AnimalDetailsViewModel : ObservableObject
{
[ObservableProperty]
private string _animalId = string.Empty;
}
Shell applies query attributes after the page constructor sets BindingContext,
so the property must raise change notification — a plain auto-property leaves the
binding stuck on its initial value.
Option 3: Complex Objects via ShellNavigationQueryParameters
Pass objects without serializing to strings:
var parameters = new ShellNavigationQueryParameters
{
{ "animal", selectedAnimal }
};
await Shell.Current.GoToAsync("animaldetails", parameters);
Receive via IQueryAttributable:
public void ApplyQueryAttributes(IDictionary<string, object> query)
{
Animal = query["animal"] as Animal;
}
Workflow: Guard Navigation
Use GetDeferral() in OnNavigating for async checks (e.g., "save unsaved changes?"):
// In AppShell.xaml.cs
protected override async void OnNavigating(ShellNavigatingEventArgs args)
{
base.OnNavigating(args);
if (hasUnsavedChanges && args.Source == ShellNavigationSource.Pop)
{
var deferral = args.GetDeferral();
bool discard = await ShowConfirmationDialog();
if (!discard)
args.Cancel();
deferral.Complete();
}
}
Tab Configuration
Bottom Tabs
Multiple ShellContent (or Tab) children inside a TabBar or FlyoutItem produce bottom tabs.
Top Tabs
Multiple ShellContent children inside a single Tab produce top tabs:
<Tab Title="Photos">
<ShellContent Title="Recent" ContentTemplate="{DataTemplate views:RecentPage}" />
<ShellContent Title="Favorites" ContentTemplate="{DataTemplate views:FavoritesPage}" />
</Tab>
Tab Bar Appearance
| Attached Property | Type | Purpose |
|---|---|---|
Shell.TabBarBackgroundColor |
Color |
Tab bar background |
Shell.TabBarForegroundColor |
Color |
Selected icon color |
Shell.TabBarTitleColor |
Color |
Selected tab title color |
Shell.TabBarUnselectedColor |
Color |
Unselected tab icon/title |
Shell.TabBarIsVisible |
bool |
Show/hide the tab bar |
<!-- Hide the tab bar on a specific page -->
<ContentPage Shell.TabBarIsVisible="False" ... />
Flyout Configuration
FlyoutBehavior
Set on Shell: Disabled, Flyout, or Locked.
<Shell FlyoutBehavior="Flyout"> ... </Shell>
FlyoutDisplayOptions
Controls how children appear in the flyout:
AsSingleItem(default) — one flyout entry for the groupAsMultipleItems— each childTabgets its own entry
<FlyoutItem Title="Animals" FlyoutDisplayOptions="AsMultipleItems">
<Tab Title="Cats" ... />
<Tab Title="Dogs" ... />
</FlyoutItem>
MenuItem (Non-Navigation Flyout Entries)
<MenuItem Text="Log Out"
Command="{Binding LogOutCommand}"
IconImageSource="logout.png" />
Back Button Behavior
Customize the back button per page:
<Shell.BackButtonBehavior>
<BackButtonBehavior Command="{Binding BackCommand}"
IconOverride="back_arrow.png"
TextOverride="Cancel"
IsVisible="True" />
</Shell.BackButtonBehavior>
Properties: Command, CommandParameter, IconOverride, TextOverride, IsVisible, IsEnabled.
Inspecting Navigation State
// Current URI location
string location = Shell.Current.CurrentState.Location.ToString();
// Current page
Page page = Shell.Current.CurrentPage;
// Navigation stack of the current tab
IReadOnlyList<Page> stack = Shell.Current.Navigation.NavigationStack;
Navigation Events
Override in AppShell:
protected override void OnNavigated(ShellNavigatedEventArgs args)
{
base.OnNavigated(args);
// args.Current, args.Previous, args.Source
}
ShellNavigationSource values: Push, Pop, PopToRoot, Insert, Remove, ShellItemChanged, ShellSectionChanged, ShellContentChanged, Unknown.
Common Pitfalls
- Eager page creation: Using
Contentdirectly instead ofContentTemplatewithDataTemplatecreates all pages at Shell init, hurting startup time. Always useContentTemplate. - Duplicate route names:
Routing.RegisterRoutethrowsArgumentExceptionif a route name matches an existing route or a visual hierarchy route. Every route must be unique across the app. - Relative routes without registration: You cannot
GoToAsync("somepage")unlesssomepagewas registered withRouting.RegisterRoute. Visual hierarchy pages use absolute//routes. - Fire-and-forget GoToAsync: Not awaiting
GoToAsynccauses race conditions and silent failures. Alwaysawaitthe call. - Wrong absolute route path: Absolute routes must match the full path through the visual hierarchy (
//FlyoutItem/Tab/ShellContent). Wrong paths produce silent no-ops, not exceptions. - Manipulating Tab.Stack directly: The navigation stack is read-only. Use
GoToAsyncfor all navigation changes. - Forgetting
GetDeferral()for async guards: Synchronous cancellation inOnNavigatingworks, but async checks requireGetDeferral()/deferral.Complete()to avoid race conditions.
References
references/shell-navigation-api.md— Full API reference for Shell hierarchy, routes, tabs, flyout, and navigation- .NET MAUI Shell Navigation
- .NET MAUI Shell Tabs
- .NET MAUI Shell Flyout
- .NET MAUI Shell Pages
Files (skills)
-
references
-
shell-navigation-api.md 9 KB
# Shell Navigation API Reference ## Shell Visual Hierarchy Shell uses a four-level hierarchy. Each level wraps the one below it: ``` Shell ├── FlyoutItem / TabBar (top-level navigation grouping) │ ├── Tab (bottom-tab grouping) │ │ ├── ShellContent (page slot; points to a ContentPage) │ │ └── ShellContent (creates top tabs within a bottom tab) │ └── Tab └── FlyoutItem / TabBar ``` - **FlyoutItem** – appears in the flyout menu. Contains one or more `Tab` children. - **TabBar** – bottom tab bar with no flyout entry. Use when the app has no flyout. - **Tab** – groups `ShellContent` objects. Multiple `ShellContent` in one `Tab` produces top tabs. - **ShellContent** – each represents a `ContentPage`. ### Implicit Conversion You can omit intermediate wrappers. Shell auto-wraps: | You write | Shell creates | |------------------------|----------------------------------------------| | `ShellContent` only | `FlyoutItem > Tab > ShellContent` | | `Tab` only | `FlyoutItem > Tab` | | `ShellContent` in `TabBar` | `TabBar > Tab > ShellContent` | This keeps simple apps concise while allowing full control when needed. ## AppShell.xaml Setup ```xml <Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:views="clr-namespace:MyApp.Views" x:Class="MyApp.AppShell" FlyoutBehavior="Flyout"> <FlyoutItem Title="Animals" Icon="animals.png"> <Tab Title="Cats"> <ShellContent Title="Domestic" ContentTemplate="{DataTemplate views:DomesticCatsPage}" /> <ShellContent Title="Wild" ContentTemplate="{DataTemplate views:WildCatsPage}" /> </Tab> <Tab Title="Dogs" Icon="dogs.png"> <ShellContent ContentTemplate="{DataTemplate views:DogsPage}" /> </Tab> </FlyoutItem> <TabBar> <ShellContent Title="Home" Icon="home.png" ContentTemplate="{DataTemplate views:HomePage}" /> <ShellContent Title="Settings" Icon="settings.png" ContentTemplate="{DataTemplate views:SettingsPage}" /> </TabBar> </Shell> ``` ## Tab Configuration ### Bottom Tabs Multiple `ShellContent` (or `Tab`) children inside a `TabBar` or `FlyoutItem` produce bottom tabs. ### Top Tabs Multiple `ShellContent` children inside a single `Tab` produce top tabs within that bottom tab: ```xml <Tab Title="Photos"> <ShellContent Title="Recent" ContentTemplate="{DataTemplate views:RecentPage}" /> <ShellContent Title="Favorites" ContentTemplate="{DataTemplate views:FavoritesPage}" /> </Tab> ``` ### TabBar Appearance (Attached Properties) Set these on any page or Shell element: | Attached Property | Type | Purpose | |--------------------------------|---------|----------------------------------| | `Shell.TabBarBackgroundColor` | `Color` | Tab bar background | | `Shell.TabBarForegroundColor` | `Color` | Foreground / selected icon color | | `Shell.TabBarTitleColor` | `Color` | Selected tab title color | | `Shell.TabBarUnselectedColor` | `Color` | Unselected tab icon/title color | | `Shell.TabBarDisabledColor` | `Color` | Disabled tab color | | `Shell.TabBarIsVisible` | `bool` | Show/hide the tab bar | ```xml <ContentPage Shell.TabBarIsVisible="False" ... /> ``` ## Flyout Configuration ### FlyoutBehavior Set on `Shell`: ```xml <Shell FlyoutBehavior="Flyout"> ... </Shell> ``` Values: `Disabled`, `Flyout`, `Locked`. ### FlyoutDisplayOptions Controls how a `FlyoutItem`'s children appear in the flyout: ```xml <FlyoutItem Title="Animals" FlyoutDisplayOptions="AsMultipleItems"> <Tab Title="Cats" ... /> <Tab Title="Dogs" ... /> </FlyoutItem> ``` - `AsSingleItem` (default) – one flyout entry for the group. - `AsMultipleItems` – each child `Tab` gets its own flyout entry. ### Flyout Item Template Customize appearance with `Shell.ItemTemplate`. BindingContext exposes `Title` and `FlyoutIcon` (FlyoutItem) or `Text` and `IconImageSource` (MenuItem): ```xml <Shell.ItemTemplate> <DataTemplate> <Grid ColumnDefinitions="Auto,*" Padding="10"> <Image Source="{Binding FlyoutIcon}" HeightRequest="24" /> <Label Grid.Column="1" Text="{Binding Title}" VerticalTextAlignment="Center" /> </Grid> </DataTemplate> </Shell.ItemTemplate> ``` ### Replacing Flyout Content ```xml <Shell.FlyoutContent> <CollectionView BindingContext="{x:Reference shell}" ItemsSource="{Binding FlyoutItems}" /> </Shell.FlyoutContent> ``` ### MenuItem (non-navigation flyout entries) ```xml <MenuItem Text="Log Out" Command="{Binding LogOutCommand}" IconImageSource="logout.png" /> ``` ## Route Registration Shell visual hierarchy items have implicit routes derived from their `Route` property (or type name). Detail pages not in the hierarchy must be registered: ```csharp // In AppShell constructor or MauiProgram Routing.RegisterRoute("animaldetails", typeof(AnimalDetailsPage)); Routing.RegisterRoute("editanimal", typeof(EditAnimalPage)); ``` ## Navigation with GoToAsync All programmatic navigation goes through `Shell.Current.GoToAsync`: ```csharp // Absolute – navigate to a specific place in the hierarchy await Shell.Current.GoToAsync("//animals/cats/domestic"); // Relative – push a registered page onto the navigation stack await Shell.Current.GoToAsync("animaldetails"); // With query string await Shell.Current.GoToAsync($"animaldetails?id={animal.Id}"); ``` ### Absolute vs Relative Routes | Prefix | Meaning | |----------|------------------------------------------------| | `//` | Absolute route from Shell root | | (none) | Relative; pushes onto the current nav stack | | `..` | Go back one level in the navigation stack | | `../` | Go back then navigate forward | ```csharp // Go back one page await Shell.Current.GoToAsync(".."); // Go back two pages await Shell.Current.GoToAsync("../.."); // Go back one page, then navigate to edit await Shell.Current.GoToAsync("../editanimal"); ``` ## Query Parameters ### QueryProperty Attribute ```csharp [QueryProperty(nameof(AnimalId), "id")] public partial class AnimalDetailsPage : ContentPage { public string AnimalId { get; set; } } // Navigate with query string: await Shell.Current.GoToAsync($"animaldetails?id={animal.Id}"); ``` ### IQueryAttributable Interface Preferred for ViewModels — gives you all parameters in one call: ```csharp public class AnimalDetailsViewModel : ObservableObject, IQueryAttributable { public void ApplyQueryAttributes(IDictionary<string, object> query) { if (query.TryGetValue("id", out var id)) AnimalId = id.ToString(); } } ``` The interface works on the page itself or on any object set as the page's `BindingContext`. ### Passing Complex Objects Use `ShellNavigationQueryParameters` (dictionary of `string` → `object`) to pass objects without serializing to strings: ```csharp var parameters = new ShellNavigationQueryParameters { { "animal", selectedAnimal } // pass the object directly }; await Shell.Current.GoToAsync("animaldetails", parameters); ``` Receive via `IQueryAttributable`: ```csharp public void ApplyQueryAttributes(IDictionary<string, object> query) { Animal = query["animal"] as Animal; } ``` ## Navigation Events Override in your `AppShell`: ```csharp protected override void OnNavigating(ShellNavigatingEventArgs args) { base.OnNavigating(args); if (hasUnsavedChanges && args.Source == ShellNavigationSource.Pop) args.Cancel(); // prevent leaving } protected override void OnNavigated(ShellNavigatedEventArgs args) { base.OnNavigated(args); // args.Current, args.Previous, args.Source } ``` For async checks, use `args.GetDeferral()` → do work → `deferral.Complete()`. `ShellNavigationSource` values: `Push`, `Pop`, `PopToRoot`, `Insert`, `Remove`, `ShellItemChanged`, `ShellSectionChanged`, `ShellContentChanged`, `Unknown`. ## Inspecting Navigation State ```csharp // Current URI location ShellNavigationState state = Shell.Current.CurrentState; string location = state.Location.ToString(); // e.g. "//animals/cats/domestic" // Current page Page page = Shell.Current.CurrentPage; // Navigation stack of the current tab IReadOnlyList<Page> stack = Shell.Current.Navigation.NavigationStack; ``` ## Back Button Behavior Customize the back button per page: ```xml <Shell.BackButtonBehavior> <BackButtonBehavior Command="{Binding BackCommand}" IconOverride="back_arrow.png" TextOverride="Cancel" /> </Shell.BackButtonBehavior> ``` Properties: `Command`, `CommandParameter`, `IconOverride`, `TextOverride`, `IsVisible`, `IsEnabled`.
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SKILL.md 15 KB
--- name: maui-shell-navigation description: >- Guide for implementing Shell-based navigation in .NET MAUI apps. Covers AppShell setup, visual hierarchy (FlyoutItem, TabBar, Tab, ShellContent), URI-based navigation with GoToAsync, route registration, query parameters, back navigation, flyout and tab configuration, navigation events, and navigation guards. Use when: setting up Shell navigation, adding tabs or flyout menus, navigating between pages with GoToAsync, passing parameters between pages, registering routes, customizing back button behavior, or guarding navigation with confirmation dialogs. Do not use for: deep linking from external URLs (see .NET MAUI deep linking documentation), data binding on pages (use maui-data-binding), dependency injection setup (use maui-dependency-injection), or NavigationPage-only apps that don't use Shell. license: MIT --- # .NET MAUI Shell Navigation Implement page navigation in .NET MAUI apps using Shell. Shell provides URI-based navigation, a flyout menu, tab bars, and a four-level visual hierarchy — all configured declaratively in XAML. ## When to Use - Setting up top-level app navigation with tabs or a flyout menu - Navigating between pages programmatically with `GoToAsync` - Passing data between pages via query parameters or object parameters - Registering detail-page routes for push navigation - Guarding navigation with confirmation dialogs (e.g., unsaved changes) - Customizing back button behavior per page ## When Not to Use - Deep linking from external URLs or app links — see [.NET MAUI deep linking docs](https://learn.microsoft.com/dotnet/maui/fundamentals/app-links) - Data binding on navigation target pages — use `maui-data-binding` - Dependency injection for pages and view models — use `maui-dependency-injection` - Apps using `NavigationPage` without Shell (different navigation API) ## Inputs - A .NET MAUI project with `AppShell.xaml` as the root shell - Pages (`ContentPage`) to navigate between - Route names for detail pages not in the visual hierarchy ## Rules That Change the Answer These are the Shell-specific decisions that are easy to get wrong. Apply them whenever they are relevant to what the user asked. | Situation | Do this | Not this | |---|---|---| | Declaring pages in `AppShell.xaml` | With `xmlns:views="clr-namespace:MyApp.Views"` declared: `<ShellContent ContentTemplate="{DataTemplate views:MyPage}" />` — the page is created on first navigation | `<ShellContent><views:MyPage /></ShellContent>`, which constructs **every** page at startup | | Navigating to a page not in the visual hierarchy | `Routing.RegisterRoute("details", typeof(DetailsPage))` first | Calling `GoToAsync("details")` unregistered — it throws at runtime | | Receiving navigation parameters | Implement `IQueryAttributable` on the **ViewModel** | Implementing it on the Page, which splits state from the BindingContext | | Passing a whole object | `ShellNavigationQueryParameters` | Serialising the object into the query string | | Any `GoToAsync` call | `await` it | Fire-and-forget — exceptions are swallowed and navigation races | | Confirming before back navigation | `ShellNavigatingEventArgs.GetDeferral()` … `deferral.Complete()` | Blocking synchronously on the dialog task | | Detecting back navigation | Check `e.Source == ShellNavigationSource.Pop` | Assuming every navigation is a back action | **Do not** propose `NavigationPage` / `PushAsync` solutions for a Shell app, and do not restructure a working `AppShell` hierarchy unless the user asked. **Answer narrowly, but completely.** Staying on topic does not mean being terse. When you show a navigation change, include the pieces needed to run it: the `AppShell.xaml` markup *and* the `Routing.RegisterRoute` call, or the `GoToAsync` call *and* the receiving `IQueryAttributable` / `[QueryProperty]` code. Where two approaches are both valid (query string vs `ShellNavigationQueryParameters`), show both and say when each fits — a single snippet the user still has to complete is a worse answer. ## Shell Visual Hierarchy Shell uses a four-level hierarchy. Each level wraps the one below it: ``` Shell ├── FlyoutItem / TabBar (top-level grouping) │ ├── Tab (bottom-tab grouping) │ │ ├── ShellContent (page slot → ContentPage) │ │ └── ShellContent (multiple = top tabs) │ └── Tab └── FlyoutItem / TabBar ``` - **FlyoutItem** — appears in the flyout menu; contains `Tab` children - **TabBar** — bottom tab bar with no flyout entry - **Tab** — groups `ShellContent`; multiple children produce top tabs - **ShellContent** — each points to a `ContentPage` ### Implicit Conversion You can omit intermediate wrappers. Shell auto-wraps: | You write | Shell creates | |------------------------------|---------------------------------------| | `ShellContent` only | `FlyoutItem > Tab > ShellContent` | | `Tab` only | `FlyoutItem > Tab` | | `ShellContent` in `TabBar` | `TabBar > Tab > ShellContent` | ## Workflow: Set Up AppShell 1. Define `AppShell.xaml` inheriting from `Shell` 2. Add `FlyoutItem` or `TabBar` elements for top-level navigation 3. Add `Tab` elements for bottom tabs; nest multiple `ShellContent` for top tabs 4. **Always use `ContentTemplate`** with `DataTemplate` so pages load on demand 5. **Give every `ShellContent` an explicit `Route`** (see below) 6. Register detail-page routes in the `AppShell` constructor > **Set `Route=` on every `ShellContent`.** If you omit it, MAUI auto-generates a > name from a shared counter — `Routing.cs` produces `D_FAULT_{TypeName}{n}`. A real > shell with three unnamed `ShellContent` elements yields routes like > `D_FAULT_ShellContent2` and `D_FAULT_ShellContent5`: the numbers are not > sequential, they depend on how many Shell elements were constructed first, and they > shift when you reorder or add pages. You cannot write a stable absolute route > (`//dashboard`) or deep link against that. An explicit `Route="dashboard"` is stable > forever. ```xml <Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:views="clr-namespace:MyApp.Views" x:Class="MyApp.AppShell" FlyoutBehavior="Flyout"> <FlyoutItem Title="Animals" Icon="animals.png"> <Tab Title="Cats"> <ShellContent Title="Domestic" Route="domesticcats" ContentTemplate="{DataTemplate views:DomesticCatsPage}" /> <ShellContent Title="Wild" Route="wildcats" ContentTemplate="{DataTemplate views:WildCatsPage}" /> </Tab> <Tab Title="Dogs" Icon="dogs.png"> <ShellContent Route="dogs" ContentTemplate="{DataTemplate views:DogsPage}" /> </Tab> </FlyoutItem> <TabBar> <ShellContent Title="Home" Icon="home.png" Route="home" ContentTemplate="{DataTemplate views:HomePage}" /> <ShellContent Title="Settings" Icon="settings.png" Route="settings" ContentTemplate="{DataTemplate views:SettingsPage}" /> </TabBar> </Shell> ``` ```csharp // AppShell.xaml.cs public partial class AppShell : Shell { public AppShell() { InitializeComponent(); Routing.RegisterRoute("animaldetails", typeof(AnimalDetailsPage)); Routing.RegisterRoute("editanimal", typeof(EditAnimalPage)); } } ``` ## Workflow: Navigate with GoToAsync All programmatic navigation uses `Shell.Current.GoToAsync`. Always `await` the call. ### Route Prefixes | Prefix | Meaning | |--------|---------------------------------------------| | `//` | Absolute route from Shell root | | (none) | Relative; pushes onto the current nav stack | | `..` | Go back one level | | `../` | Go back then navigate forward | ### Navigation Examples ```csharp // 1. Absolute — switch to a specific hierarchy location await Shell.Current.GoToAsync("//animals/cats/domestic"); // 2. Relative — push a registered detail page await Shell.Current.GoToAsync("animaldetails"); // 3. With query string parameters await Shell.Current.GoToAsync($"animaldetails?id={animal.Id}"); // 4. Go back one page await Shell.Current.GoToAsync(".."); // 5. Go back two pages await Shell.Current.GoToAsync("../.."); // 6. Go back one page, then push a different page await Shell.Current.GoToAsync("../editanimal"); ``` ## Workflow: Pass Data Between Pages ### Option 1: IQueryAttributable (Preferred) Implement on ViewModels to receive all parameters in one call: ```csharp public class AnimalDetailsViewModel : ObservableObject, IQueryAttributable { public void ApplyQueryAttributes(IDictionary<string, object> query) { if (query.TryGetValue("id", out var id)) AnimalId = id.ToString(); } } ``` ### Option 2: QueryProperty Attribute Apply on the **ViewModel** class (or the page, if it genuinely owns the state). Prefer `IQueryAttributable` on the ViewModel — it keeps navigation state with the `BindingContext` and handles multiple parameters in one call: ```csharp [QueryProperty(nameof(AnimalId), "id")] public partial class AnimalDetailsViewModel : ObservableObject { [ObservableProperty] private string _animalId = string.Empty; } ``` Shell applies query attributes *after* the page constructor sets `BindingContext`, so the property must raise change notification — a plain auto-property leaves the binding stuck on its initial value. ### Option 3: Complex Objects via ShellNavigationQueryParameters Pass objects without serializing to strings: ```csharp var parameters = new ShellNavigationQueryParameters { { "animal", selectedAnimal } }; await Shell.Current.GoToAsync("animaldetails", parameters); ``` Receive via `IQueryAttributable`: ```csharp public void ApplyQueryAttributes(IDictionary<string, object> query) { Animal = query["animal"] as Animal; } ``` ## Workflow: Guard Navigation Use `GetDeferral()` in `OnNavigating` for async checks (e.g., "save unsaved changes?"): ```csharp // In AppShell.xaml.cs protected override async void OnNavigating(ShellNavigatingEventArgs args) { base.OnNavigating(args); if (hasUnsavedChanges && args.Source == ShellNavigationSource.Pop) { var deferral = args.GetDeferral(); bool discard = await ShowConfirmationDialog(); if (!discard) args.Cancel(); deferral.Complete(); } } ``` ## Tab Configuration ### Bottom Tabs Multiple `ShellContent` (or `Tab`) children inside a `TabBar` or `FlyoutItem` produce bottom tabs. ### Top Tabs Multiple `ShellContent` children inside a single `Tab` produce top tabs: ```xml <Tab Title="Photos"> <ShellContent Title="Recent" ContentTemplate="{DataTemplate views:RecentPage}" /> <ShellContent Title="Favorites" ContentTemplate="{DataTemplate views:FavoritesPage}" /> </Tab> ``` ### Tab Bar Appearance | Attached Property | Type | Purpose | |--------------------------------|---------|--------------------------------| | `Shell.TabBarBackgroundColor` | `Color` | Tab bar background | | `Shell.TabBarForegroundColor` | `Color` | Selected icon color | | `Shell.TabBarTitleColor` | `Color` | Selected tab title color | | `Shell.TabBarUnselectedColor` | `Color` | Unselected tab icon/title | | `Shell.TabBarIsVisible` | `bool` | Show/hide the tab bar | ```xml <!-- Hide the tab bar on a specific page --> <ContentPage Shell.TabBarIsVisible="False" ... /> ``` ## Flyout Configuration ### FlyoutBehavior Set on `Shell`: `Disabled`, `Flyout`, or `Locked`. ```xml <Shell FlyoutBehavior="Flyout"> ... </Shell> ``` ### FlyoutDisplayOptions Controls how children appear in the flyout: - `AsSingleItem` (default) — one flyout entry for the group - `AsMultipleItems` — each child `Tab` gets its own entry ```xml <FlyoutItem Title="Animals" FlyoutDisplayOptions="AsMultipleItems"> <Tab Title="Cats" ... /> <Tab Title="Dogs" ... /> </FlyoutItem> ``` ### MenuItem (Non-Navigation Flyout Entries) ```xml <MenuItem Text="Log Out" Command="{Binding LogOutCommand}" IconImageSource="logout.png" /> ``` ## Back Button Behavior Customize the back button per page: ```xml <Shell.BackButtonBehavior> <BackButtonBehavior Command="{Binding BackCommand}" IconOverride="back_arrow.png" TextOverride="Cancel" IsVisible="True" /> </Shell.BackButtonBehavior> ``` Properties: `Command`, `CommandParameter`, `IconOverride`, `TextOverride`, `IsVisible`, `IsEnabled`. ## Inspecting Navigation State ```csharp // Current URI location string location = Shell.Current.CurrentState.Location.ToString(); // Current page Page page = Shell.Current.CurrentPage; // Navigation stack of the current tab IReadOnlyList<Page> stack = Shell.Current.Navigation.NavigationStack; ``` ## Navigation Events Override in `AppShell`: ```csharp protected override void OnNavigated(ShellNavigatedEventArgs args) { base.OnNavigated(args); // args.Current, args.Previous, args.Source } ``` `ShellNavigationSource` values: `Push`, `Pop`, `PopToRoot`, `Insert`, `Remove`, `ShellItemChanged`, `ShellSectionChanged`, `ShellContentChanged`, `Unknown`. ## Common Pitfalls - **Eager page creation**: Using `Content` directly instead of `ContentTemplate` with `DataTemplate` creates all pages at Shell init, hurting startup time. Always use `ContentTemplate`. - **Duplicate route names**: `Routing.RegisterRoute` throws `ArgumentException` if a route name matches an existing route or a visual hierarchy route. Every route must be unique across the app. - **Relative routes without registration**: You cannot `GoToAsync("somepage")` unless `somepage` was registered with `Routing.RegisterRoute`. Visual hierarchy pages use absolute `//` routes. - **Fire-and-forget GoToAsync**: Not awaiting `GoToAsync` causes race conditions and silent failures. Always `await` the call. - **Wrong absolute route path**: Absolute routes must match the full path through the visual hierarchy (`//FlyoutItem/Tab/ShellContent`). Wrong paths produce silent no-ops, not exceptions. - **Manipulating Tab.Stack directly**: The navigation stack is read-only. Use `GoToAsync` for all navigation changes. - **Forgetting `GetDeferral()` for async guards**: Synchronous cancellation in `OnNavigating` works, but async checks require `GetDeferral()` / `deferral.Complete()` to avoid race conditions. ## References - `references/shell-navigation-api.md` — Full API reference for Shell hierarchy, routes, tabs, flyout, and navigation - [.NET MAUI Shell Navigation](https://learn.microsoft.com/dotnet/maui/fundamentals/shell/navigation) - [.NET MAUI Shell Tabs](https://learn.microsoft.com/dotnet/maui/fundamentals/shell/tabs) - [.NET MAUI Shell Flyout](https://learn.microsoft.com/dotnet/maui/fundamentals/shell/flyout) - [.NET MAUI Shell Pages](https://learn.microsoft.com/dotnet/maui/fundamentals/shell/pages)
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