Merge pull request #1829 from PrismLibrary/modal

Enhanced Modal Logic & Exception Handling

Sandbox/Xamarin/HelloWorld/HelloWorld/HelloWorld.UWP/App.xaml.cs

@@ -39,13 +39,9 @@ public App()
         /// <param name="e">Details about the launch request and process.</param>
         protected override void OnLaunched(LaunchActivatedEventArgs e)
         {
-
-
-            Frame rootFrame = Window.Current.Content as Frame;
-
             // Do not repeat app initialization when the Window already has content,
             // just ensure that the window is active
-            if (rootFrame == null)
+            if (!(Window.Current.Content is Frame rootFrame))
             {
                 // Create a Frame to act as the navigation context and navigate to the first page
                 rootFrame = new Frame();

Sandbox/Xamarin/HelloWorld/HelloWorld/HelloWorld/HelloWorld.csproj

@@ -27,14 +27,5 @@
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>Resources.Designer.cs</LastGenOutput>
     </EmbeddedResource>
-    <EmbeddedResource Update="Views\DemoDialog.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Views\DialogDemoPage.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Views\UserAlert.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
   </ItemGroup>
 </Project>

Sandbox/Xamarin/HelloWorld/ModuleA/ViewModels/ViewAViewModel.cs

@@ -29,7 +29,6 @@ public string Message
             set => SetProperty(ref _message, value);
         }
 
-
         public bool CanNavigate
         {
             get { return _canNavigate; }

Sandbox/Xamarin/HelloWorld/ModuleA/Views/ViewA.xaml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
-             xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
+             xmlns:prism="http://prismlibrary.com"
              prism:ViewModelLocator.AutowireViewModel="True"
              x:Class="ModuleA.Views.ViewA"
              Padding="{OnPlatform iOS='0,20,0,0'}"
@@ -23,6 +23,12 @@
         <Label Text="{Binding Message}" />
         <Label Text="{Binding IsActive, StringFormat='IsActive: {0}'}" />
         <Button Command="{Binding NavigateCommand}" Text="Navigate" />
+        <Button Text="View B"
+                Command="{prism:NavigateTo ViewB}" />
+        <Button Text="Select Tab C"
+                Command="{prism:SelectTab ViewC}" />
+        <Button Text="Go Back"
+                Command="{prism:GoBack}" />
     </StackLayout>
 
 </ContentPage>

Sandbox/Xamarin/HelloWorld/ModuleA/Views/ViewB.xaml

@@ -2,22 +2,24 @@
 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:local="clr-namespace:ModuleA.Views"
-             xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
+             xmlns:prism="http://prismlibrary.com"
              prism:ViewModelLocator.AutowireViewModel="True"
              x:Class="ModuleA.Views.ViewB"
              x:Name="viewB"
+             Padding="{OnPlatform iOS='0,20,0,0'}"
              Title="View B">
-    <ContentPage.Padding>
-        <OnPlatform x:TypeArguments="Thickness">
-            <On Platform="iOS" Value="0,20,0,0" />
-        </OnPlatform>
-    </ContentPage.Padding>
 
     <!--<local:PartialViewB prism:ViewModelLocator.AutowirePartialView="{x:Reference viewB}" />-->
     <StackLayout>
         <Label Text="{Binding Title}" VerticalOptions="Center" HorizontalOptions="Center" />
         <Label Text="{Binding IsActive}" />
         <Button Command="{Binding NavigateCommand}" Text="Navigate" />
+        <Button Text="View C"
+                Command="{prism:NavigateTo ViewC}" />
+        <Button Text="Select Tab C"
+                Command="{prism:SelectTab ViewC}" />
+        <Button Text="Go Back"
+                Command="{prism:GoBack}" />
     </StackLayout>
 
 </ContentPage>

Sandbox/Xamarin/HelloWorld/ModuleA/Views/ViewC.xaml

@@ -1,17 +1,19 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
-             xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
+             xmlns:prism="http://prismlibrary.com"
              prism:ViewModelLocator.AutowireViewModel="True"
              x:Class="ModuleA.Views.ViewC"
+             Padding="{OnPlatform iOS='0,20,0,0'}"
              Title="View C">
-    <ContentPage.Padding>
-        <OnPlatform x:TypeArguments="Thickness">
-            <On Platform="iOS" Value="0,20,0,0" />
-        </OnPlatform>
-    </ContentPage.Padding>
-  <StackLayout>
+    <StackLayout>
     <Label Text="{Binding Title}" VerticalOptions="Center" HorizontalOptions="Center" />
-    <Button Command="{Binding NavigateCommand}" Text="Navigate" />
-  </StackLayout>
+        <Button Command="{Binding NavigateCommand}" Text="Navigate" />
+        <Button Text="View B"
+                Command="{prism:NavigateTo ViewB}" />
+        <Button Text="Select Tab A"
+                Command="{prism:SelectTab ViewA}" />
+        <Button Text="Go Back"
+                Command="{prism:GoBack}" />
+    </StackLayout>
 </ContentPage>

Source/Prism/Common/ParametersBase.cs

@@ -58,8 +58,21 @@ protected ParametersBase(string query)
             }
         }
 
-        public object this[string key] =>
-            _entries.FirstOrDefault(x => string.Compare(x.Key, key, StringComparison.Ordinal) == 0);
+        public object this[string key]
+        {
+            get
+            {
+                foreach(var entry in _entries)
+                {
+                    if(string.Compare(entry.Key, key, StringComparison.Ordinal) == 0)
+                    {
+                        return entry.Value;
+                    }
+                }
+
+                return null;
+            }
+        }
 
         public int Count => _entries.Count;
 

Source/Xamarin/Prism.DI.Forms.Tests/Fixtures/PrismApplicationFixture.cs

@@ -132,16 +132,14 @@ public async Task Navigate_UnregisteredView_ThrowException()
 
             Assert.False(result.Success);
             Assert.NotNull(result.Exception);
-#if Autofac
-            Assert.IsType<ComponentNotRegisteredException>(result.Exception);
-#elif DryIoc
-            Assert.IsType<ContainerException>(result.Exception);
-#elif Ninject
-            Assert.IsType<ActivationException>(result.Exception);
+            Assert.IsType<NavigationException>(result.Exception);
+            Assert.Equal(NavigationException.NoPageIsRegistered, result.Exception.Message);
+#if DryIoc
+            Assert.IsType<ContainerException>(result.Exception.InnerException);
 #elif Unity
-            Assert.IsType<NullReferenceException>(result.Exception);
+            Assert.IsType<NullReferenceException>(result.Exception.InnerException);
 #endif
-            Assert.Contains("missing", result.Exception.ToString(), StringComparison.OrdinalIgnoreCase);
+            Assert.Contains("missing", result.Exception.InnerException.ToString(), StringComparison.OrdinalIgnoreCase);
         }
 
         [Theory]

Source/Xamarin/Prism.Forms/Common/PageUtilities.cs

@@ -293,20 +293,26 @@ internal static bool HasDirectNavigationPageParent(Page page)
             return page?.Parent != null && page?.Parent is NavigationPage;
         }
 
-        internal static bool HasNavigationPageParent(Page page)
+        internal static bool HasNavigationPageParent(Page page) =>
+            HasNavigationPageParent(page, out var _);
+
+        internal static bool HasNavigationPageParent(Page page, out NavigationPage navigationPage)
         {
             if (page?.Parent != null)
             {
-                if (page.Parent is NavigationPage)
+                if (page.Parent is NavigationPage navParent)
                 {
+                    navigationPage = navParent;
                     return true;
                 }
-                else if (page.Parent is TabbedPage || page.Parent is CarouselPage)
+                else if ((page.Parent is TabbedPage || page.Parent is CarouselPage) && page.Parent?.Parent is NavigationPage navigationParent)
                 {
-                    return page.Parent.Parent != null && page.Parent.Parent is NavigationPage;
+                    navigationPage = navigationParent;
+                    return true;
                 }
             }
 
+            navigationPage = null;
             return false;
         }
 

Source/Xamarin/Prism.Forms/Navigation/NavigationException.cs

@@ -0,0 +1,32 @@
+using System;
+using Xamarin.Forms;
+
+namespace Prism.Navigation
+{
+    public class NavigationException : Exception
+    {
+        public const string CannotPopApplicationMainPage = "Cannot Pop Application MainPage";
+        public const string CannotGoBackFromRoot = "Cannot GoBack from NavigationPage Root.";
+        public const string GoBackToRootRequiresNavigationPage = "GoBackToRootAsync can only be called when the calling Page is within a NavigationPage.";
+        public const string RelativeNavigationRequiresNavigationPage = "Removing views using the relative '../' syntax while navigating is only supported within a NavigationPage";
+        public const string IConfirmNavigationReturnedFalse = "IConfirmNavigation returned false";
+        public const string NoPageIsRegistered = "No Page has been registered with the provided key";
+        public const string ErrorCreatingPage = "An error occurred while resolving the page. This is most likely the result of invalid XAML or other type initialization exception";
+        public const string UnknownException = "An unknown error occurred. You may need to specify whether to Use Modal Navigation or not.";
+
+        public NavigationException()
+        {
+        }
+
+        public NavigationException(string message, Page page) : this(message, page, null)
+        {
+        }
+
+        public NavigationException(string message, Page page, Exception innerException) : base(message, innerException)
+        {
+            Page = page;
+        }
+
+        public Page Page { get; }
+    }
+}