Merge pull request #2098 from unoplatform/dev/nr/fixingbacknav

fix: free viewmodel and prevent caching of page on back
unoplatform · Dec 7, 2023 · eee74a7 · eee74a7
2 parents 0e8c152 + f24a898
commit eee74a7
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Showing 5 changed files with 33 additions and 3 deletions.
diff --git a/src/Uno.Extensions.Navigation.UI/Navigators/FrameNavigator.cs b/src/Uno.Extensions.Navigation.UI/Navigators/FrameNavigator.cs
@@ -28,6 +28,7 @@ public override void ControlInitialize()
 
 		if (Control is not null)
 		{
+			Control.Navigating += Frame_Navigating;
 			Control.Navigated += Frame_Navigated;
 		}
 	}
@@ -249,6 +250,22 @@ viewType is null ||
 		return responseRoute;
 	}
 
+	private void Frame_Navigating(object sender, NavigatingCancelEventArgs e)
+	{
+		if( e.NavigationMode==NavigationMode.Back &&
+			!e.Cancel &&
+			Control?.Content is Page currentPage)
+		{
+			if (Logger.IsEnabled(LogLevel.Debug)) Logger.LogDebugMessage($"Frame has navigating to previous page");
+
+			// Force ViewModel to be unset
+			currentPage.DataContext = null;
+			// Force page to be disposed
+			currentPage.NavigationCacheMode = NavigationCacheMode.Disabled;
+		}
+	}
+
+
 	private void Frame_Navigated(object sender, NavigationEventArgs e)
 	{
 		if (Logger.IsEnabled(LogLevel.Debug)) Logger.LogDebugMessage($"Frame has navigated to page '{e.SourcePageType.Name}'");

diff --git a/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveOneViewModel.cs b/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveOneViewModel.cs
@@ -11,7 +11,7 @@ public async Task GoToTwo()
 
 	public async Task GoToTwoData()
 	{
-		await Navigator.NavigateDataAsync(this, data:new TwoModel(new ReactiveWidget("From Two",56)));
+		await Navigator.NavigateDataAsync(this, data:new TwoModel(new ReactiveWidget("From One",56)));
 	}
 
 	public async Task GoToThree()
@@ -21,7 +21,7 @@ public async Task GoToThree()
 
 	public async Task GoToThreeData()
 	{
-		await Navigator.NavigateDataAsync(this, data: new ThreeModel(new ReactiveWidget("From Three", 56)));
+		await Navigator.NavigateDataAsync(this, data: new ThreeModel(new ReactiveWidget("From One", 56)));
 	}
 
 	public async Task ShowDialog()

diff --git a/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveThreePage.xaml b/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveThreePage.xaml
@@ -7,6 +7,7 @@
 	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 	xmlns:uen="using:Uno.Extensions.Navigation.UI"
 	Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
+	NavigationCacheMode="Required"
 	mc:Ignorable="d">
 
 	<Grid>

diff --git a/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveTwoPage.xaml b/testing/TestHarness/TestHarness.Shared/Ext/Navigation/Reactive/ReactiveTwoPage.xaml
@@ -7,6 +7,7 @@
 	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 	xmlns:uen="using:Uno.Extensions.Navigation.UI"
 	Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
+	NavigationCacheMode="Required"
 	mc:Ignorable="d">
 	<Grid>
 		<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">

diff --git a/testing/TestHarness/TestHarness.UITest/Ext/Navigation/Reactive/Given_Reactive.cs b/testing/TestHarness/TestHarness.UITest/Ext/Navigation/Reactive/Given_Reactive.cs
@@ -91,10 +91,21 @@ public void When_ReactiveDependsOnWithData()
 
 		App.WaitElement("OnePageToTwoPageViewModelButton");
 		var screenBefore = TakeScreenshot("When_PageNavigationViewModel_Before");
+
+		// Iterate through pages 1 to 3 - this caused an issue
+		// where NavigationCacheMode is set to required
+		// see https://github.com/unoplatform/uno.extensions/issues/2097
+		App.WaitThenTap("OnePageToTwoPageViewModelButton");
+		App.WaitThenTap("TwoPageToThreePageViewModelButton");
+		App.WaitThenTap("ThreePageBackViewModelButton");
+		App.WaitThenTap("TwoPageBackViewModelButton");
+		App.WaitElement("OnePageToTwoPageViewModelButton");
+
+
 		App.WaitThenTap("OnePageToThreePageDataButton");
 		App.WaitElement("ThreePageWidgetNameTextBlock");
 		var text = App.GetText("ThreePageWidgetNameTextBlock");
-		Assert.AreEqual("From Three", text);
+		Assert.AreEqual("From One", text);
 
 		App.WaitThenTap("ThreePageBackViewModelButton");
 		text = App.GetText("TwoPageWidgetNameTextBlock");