Adding select tab API to INavigationService

src/Maui/Prism.Maui/Navigation/INavigationService.cs

@@ -33,9 +33,18 @@ public interface INavigationService
     /// </summary>
     /// <param name="uri">The Uri to navigate to</param>
     /// <param name="parameters">The navigation parameters</param>
+    /// <returns><see cref="INavigationResult"/> indicating whether the request was successful or if there was an encountered <see cref="Exception"/>.</returns>
     /// <remarks>Navigation parameters can be provided in the Uri and by using the <paramref name="parameters"/>.</remarks>
     /// <example>
-    /// NavigateAsync(new Uri("MainPage?id=3&amp;name=brian", UriKind.RelativeSource), parameters);
+    /// NavigateAsync(new Uri("MainPage?id=3&amp;name=Brian", UriKind.RelativeSource), parameters);
     /// </example>
     Task<INavigationResult> NavigateAsync(Uri uri, INavigationParameters parameters);
+
+    /// <summary>
+    /// Selects a Tab of the TabbedPage parent.
+    /// </summary>
+    /// <param name="name">The name of the tab to select</param>
+    /// <param name="parameters">The navigation parameters</param>
+    /// <returns><see cref="INavigationResult"/> indicating whether the request was successful or if there was an encountered <see cref="Exception"/>.</returns>
+    Task<INavigationResult> SelectTabAsync(string name, INavigationParameters parameters);
 }

src/Maui/Prism.Maui/Navigation/INavigationServiceExtensions.cs

@@ -117,6 +117,15 @@ public static void OnNavigationError(this Task<INavigationResult> navigationTask
         });
     }
 
+    /// <summary>
+    /// Selects a tab programatically
+    /// </summary>
+    /// <param name="navigationService"></param>
+    /// <param name="tabName">The name of the tab to select</param>
+    /// <returns>The <see cref="INavigationResult"/>.</returns>
+    public static Task<INavigationResult> SelectTabAsync(this INavigationService navigationService, string tabName) =>
+        navigationService.SelectTabAsync(tabName, new NavigationParameters());
+
     private static INavigationParameters GetNavigationParameters((string Key, object Value)[] parameters)
     {
         var navParams = new NavigationParameters();

src/Maui/Prism.Maui/Navigation/PageNavigationService.cs

@@ -35,6 +35,10 @@ protected Window Window
             {
                 _window = _pageAccessor.Page.GetParentWindow();
             }
+            else
+            {
+                _window = _windowManager.Windows.OfType<PrismWindow>().FirstOrDefault();
+            }
 
             return _window;
         }
@@ -49,6 +53,7 @@ protected Window Window
     /// <param name="container">The <see cref="IContainerProvider"/> that will be used to resolve pages for navigation.</param>
     /// <param name="windowManager">The <see cref="IWindowManager"/> that will let the NavigationService retrieve, open or close the app Windows.</param>
     /// <param name="eventAggregator">The <see cref="IEventAggregator"/> that will raise <see cref="NavigationRequestEvent"/>.</param>
+    /// <param name="pageAccessor">The <see cref="IPageAccessor"/> that will let the NavigationService retrieve the <see cref="Page"/> for the current scope.</param>q
     public PageNavigationService(IContainerProvider container,
         IWindowManager windowManager,
         IEventAggregator eventAggregator,
@@ -319,6 +324,56 @@ public virtual async Task<INavigationResult> NavigateAsync(Uri uri, INavigationP
         }
     }
 
+    /// <summary>
+    /// Selects a Tab of the TabbedPage parent.
+    /// </summary>
+    /// <param name="tabName">The name of the tab to select</param>
+    /// <param name="parameters">The navigation parameters</param>
+    /// <returns><see cref="INavigationResult"/> indicating whether the request was successful or if there was an encountered <see cref="Exception"/>.</returns>
+    public virtual async Task<INavigationResult> SelectTabAsync(string tabName, INavigationParameters parameters)
+    {
+        try
+        {
+            var tabbedPage = GetTabbedPage(_pageAccessor.Page);
+            TabbedPage GetTabbedPage(Element page) =>
+                page switch
+                {
+                    TabbedPage tabbedPage => tabbedPage,
+                    null => null,
+                    _ => GetTabbedPage(page.Parent)
+                };
+
+            if (tabbedPage is null)
+                throw new NullReferenceException("The Page is null.");
+
+            var parts = tabName.Split('|');
+            Page selectedChild = null;
+            if (parts.Length == 1)
+                selectedChild = tabbedPage.Children.FirstOrDefault(x => ViewModelLocator.GetNavigationName(x) == tabName || (x is NavigationPage navPage && ViewModelLocator.GetNavigationName(navPage.RootPage) == tabName));
+            else if (parts.Length == 2)
+                selectedChild = tabbedPage.Children.FirstOrDefault(x => x is NavigationPage navPage && ViewModelLocator.GetNavigationName(navPage) == parts[0] && ViewModelLocator.GetNavigationName(navPage.RootPage) == parts[1]);
+            else
+                throw new NavigationException($"Invalid Tab Name: {tabName}");
+
+            if (selectedChild is null)
+                throw new NavigationException($"No Tab found with the Name: {tabName}");
+
+            var navigatedFromPage = _pageAccessor.Page;
+            if (!await MvvmHelpers.CanNavigateAsync(navigatedFromPage, parameters))
+                throw new NavigationException(NavigationException.IConfirmNavigationReturnedFalse, navigatedFromPage);
+
+            tabbedPage.CurrentPage = selectedChild;
+            MvvmHelpers.OnNavigatedFrom(navigatedFromPage, parameters);
+            MvvmHelpers.OnNavigatedTo(selectedChild, parameters);
+
+            return new NavigationResult();
+        }
+        catch (Exception ex)
+        {
+            return new NavigationResult(ex);
+        }
+    }
+
     /// <summary>
     /// Processes the Navigation for the Queued navigation segments
     /// </summary>
@@ -605,7 +660,7 @@ await DoNavigateAction(currentPage, nextSegment, nextPage, parameters, async ()
 
         var nextSegmentType = Registry.GetViewType(UriParsingHelper.GetSegmentName(nextSegment));
 
-        //we must recreate the NavigationPage everytime or the transitions on iOS will not work properly, unless we meet the two scenarios below
+        //we must recreate the NavigationPage every time or the transitions on iOS will not work properly, unless we meet the two scenarios below
         bool detailIsNavPage = false;
         bool reuseNavPage = false;
         if (detail is NavigationPage navPage)

tests/Maui/Prism.DryIoc.Maui.Tests/Fixtures/Navigation/NavigationTests.cs

@@ -249,7 +249,7 @@ public async Task GoBack_Issue2232()
     }
 
     [Fact]
-    public async Task TabbedPageSelectTabSetsCurrentTab()
+    public async Task TabbedPage_SelectTabSets_CurrentTab()
     {
         var mauiApp = CreateBuilder(prism => prism.CreateWindow("TabbedPage?createTab=MockViewA&createTab=MockViewB&selectedTab=MockViewB"))
             .Build();
@@ -262,7 +262,7 @@ public async Task TabbedPageSelectTabSetsCurrentTab()
     }
 
     [Fact]
-    public async Task TabbedPageSelectTabSetsCurrentTabWithNavigationPageTab()
+    public async Task TabbedPage_SelectTab_SetsCurrentTab_WithNavigationPageTab()
     {
         var mauiApp = CreateBuilder(prism => prism.CreateWindow("TabbedPage?createTab=NavigationPage%2FMockViewA&createTab=NavigationPage%2FMockViewB&selectedTab=NavigationPage|MockViewB"))
             .Build();
@@ -276,11 +276,67 @@ public async Task TabbedPageSelectTabSetsCurrentTabWithNavigationPageTab()
         Assert.IsType<MockViewB>(navPage.CurrentPage);
     }
 
+    [Fact]
+    public async Task TabbedPage_SelectsNewTab()
+    {
+        var mauiApp = CreateBuilder(prism => prism
+            .CreateWindow(nav => nav.CreateBuilder()
+                .AddTabbedSegment(s => s.CreateTab("MockViewA")
+                                                       .CreateTab("MockViewB")
+                                                       .CreateTab("MockViewC"))
+                .NavigateAsync()))
+            .Build();
+        var window = GetWindow(mauiApp);
+        Assert.IsAssignableFrom<TabbedPage>(window.Page);
+        var tabbed = window.Page as TabbedPage;
+
+        Assert.NotNull(tabbed);
+
+        Assert.IsType<MockViewA>(tabbed.CurrentPage);
+        var mockViewA = tabbed.CurrentPage;
+        var mockViewANav = Prism.Navigation.Xaml.Navigation.GetNavigationService(mockViewA);
+
+        await mockViewANav.SelectTabAsync("MockViewB");
+
+        Assert.IsNotType<MockViewA>(tabbed.CurrentPage);
+        Assert.IsType<MockViewB>(tabbed.CurrentPage);
+    }
+
+    [Fact]
+    public async Task TabbedPage_SelectsNewTab_WithNavigationParameters()
+    {
+        var mauiApp = CreateBuilder(prism => prism
+            .CreateWindow(nav => nav.CreateBuilder()
+                .AddTabbedSegment(s => s.CreateTab("MockViewA")
+                                                       .CreateTab("MockViewB")
+                                                       .CreateTab("MockViewC"))
+                .NavigateAsync()))
+            .Build();
+        var window = GetWindow(mauiApp);
+        Assert.IsAssignableFrom<TabbedPage>(window.Page);
+        var tabbed = window.Page as TabbedPage;
+
+        Assert.NotNull(tabbed);
+
+        Assert.IsType<MockViewA>(tabbed.CurrentPage);
+        var mockViewA = tabbed.CurrentPage;
+        var mockViewANav = Prism.Navigation.Xaml.Navigation.GetNavigationService(mockViewA);
+
+        var expectedMessage = nameof(TabbedPage_SelectsNewTab_WithNavigationParameters);
+        await mockViewANav.SelectTabAsync("MockViewB", new NavigationParameters { { "Message", expectedMessage } });
+
+        Assert.IsNotType<MockViewA>(tabbed.CurrentPage);
+        Assert.IsType<MockViewB>(tabbed.CurrentPage);
+
+        var viewModel = tabbed.CurrentPage.BindingContext as MockViewBViewModel;
+        Assert.Equal(expectedMessage, viewModel?.Message);
+    }
+
     [Fact]
     public async Task NavigationPage_DoesNotHave_MauiPage_AsRootPage()
     {
         var mauiApp = CreateBuilder(prism => prism
-            .OnAppStart("NavigationPage/MockViewA"))
+            .CreateWindow("NavigationPage/MockViewA"))
             .Build();
         var window = GetWindow(mauiApp);
 
@@ -298,7 +354,7 @@ public async Task NavigationPage_DoesNotHave_MauiPage_AsRootPage()
     public async Task NavigationPage_UsesRootPageTitle_WithTabbedParent()
     {
         var mauiApp = CreateBuilder(prism => prism
-            .OnAppStart(n => n.CreateBuilder()
+            .CreateWindow(n => n.CreateBuilder()
                 .AddTabbedSegment(s => s
                     .CreateTab(t => t.AddNavigationPage()
                                                 .AddSegment("MockViewA")))

tests/Maui/Prism.DryIoc.Maui.Tests/Mocks/ViewModels/MockViewModelBase.cs

@@ -2,7 +2,7 @@
 
 namespace Prism.DryIoc.Maui.Tests.Mocks.ViewModels;
 
-public abstract class MockViewModelBase : IActiveAware, IConfirmNavigation
+public abstract class MockViewModelBase : IActiveAware, INavigationAware, IConfirmNavigation
 {
     private readonly IPageAccessor _pageAccessor;
 
@@ -14,6 +14,11 @@ protected MockViewModelBase(IPageAccessor pageAccessor, INavigationService navig
         NavigationService = navigationService;
     }
 
+    public string Message { get; private set; }
+
+    private List<string> _actions = [];
+    public IEnumerable<string> Actions => _actions;
+
     public INavigationService NavigationService { get; }
 
     public Task<INavigationResult> GoBack() => NavigationService.GoBackAsync();
@@ -26,6 +31,21 @@ protected MockViewModelBase(IPageAccessor pageAccessor, INavigationService navig
 
     public bool IsActive { get; set; }
 
-    public bool CanNavigate(INavigationParameters parameters) =>
-        !StopNavigation;
+    public bool CanNavigate(INavigationParameters parameters)
+    {
+        _actions.Add(nameof(CanNavigate));
+        return !StopNavigation;
+    }
+
+    public void OnNavigatedFrom(INavigationParameters parameters)
+    {
+        _actions.Add(nameof(OnNavigatedFrom));
+    }
+
+    public void OnNavigatedTo(INavigationParameters parameters)
+    {
+        _actions.Add(nameof(OnNavigatedTo));
+        if (parameters.TryGetValue<string>("Message", out var message))
+            Message = message;
+    }
 }