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Using the Visual Studio 2017 Universal Windows Templates I created a test UWP App using Prism. It all works fine untill I added a new blank page to the app. The view is called:

AbcPage

The XAML

<Page
x:Class="UI_Test_1.Views.AbcPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="using:UI_Test_1.Views"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:prismMvvm="using:Prism.Windows.Mvvm"
prismMvvm:ViewModelLocator.AutoWireViewModel="True"
Background="ThemeResource ApplicationPageBackgroundThemeBrush"
mc:Ignorable="d">

<Grid>
 <Button Click="Button_Click" Content="test" />
</Grid>

I added the

 xmlns:prismMvvm="using:Prism.Windows.Mvvm"
 prismMvvm:ViewModelLocator.AutoWireViewModel="True"

The code behind is thus:

 namespace UI_Test_1.Views

 public sealed partial class AbcPage : Page
 
 AbcPageViewModel viewModel => DataContext as AbcPageViewModel;
 public AbcPage()
 
 this.InitializeComponent();
 
 private void Button_Click(object sender, RoutedEventArgs e)
 
 var vm = viewModel;//this is null
 
 

And finally my ViewModel:

namespace UI_Test_1.ViewModels

 public class AbcPageViewModel : ViewModelBase
 
 public AbcPageViewModel()
 
 //never called
 
 
 

The conventions appear to be correct or have I made a mistake? Why is the

 AbcViewModel

null? How do I debug this?

For using prism early releases within uwp, you need config more ting base on native uwp project, such as App class and Page class. Certainly, the official has provide code sample you could refer.

public sealed partial class App : PrismUnityApplication

 public App()
 
 InitializeComponent();
 

 protected override UIElement CreateShell(Frame rootFrame)
 
 var shell = Container.Resolve<AppShell>();
 shell.SetContentFrame(rootFrame);
 return shell;
 

 protected override Task OnInitializeAsync(IActivatedEventArgs args)
 
 Container.RegisterInstance<IResourceLoader>(new ResourceLoaderAdapter(new ResourceLoader()));
 return base.OnInitializeAsync(args);
 

 protected override Task OnLaunchApplicationAsync(LaunchActivatedEventArgs args)
 
 NavigationService.Navigate(PageTokens.Main.ToString(), null);
 return Task.FromResult(true);
 

For last 7.2 version that does not release has new usage mode. For more please check this link.

sealed partial class App : PrismApplication

 public static IPlatformNavigationService NavigationService get; private set; 

 public App()
 
 InitializeComponent();
 

 public override void RegisterTypes(IContainerRegistry container)
 
 container.RegisterForNavigation<MainPage, MainPageViewModel>(nameof(Views.MainPage));
 

 public override void OnInitialized()
 
 NavigationService = Prism.Navigation.NavigationService
 .Create(new Frame(), Gestures.Back, Gestures.Forward, Gestures.Refresh);
 NavigationService.SetAsWindowContent(Window.Current, true);
 

 public override void OnStart(StartArgs args)
 
 NavigationService.NavigateAsync(nameof(Views.MainPage));
 

I made a mistake with the naming conventions. If your page is AbcPage then the viewmodel should be AbcViewModel NOT AbcPageViewModel.