Navigation - cant go back in basic MainPage / SecondPage scenario , what am I doing wrong ? #2301
Replies: 4 comments 7 replies
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Hi @DomagojJugovich, as you mentioned here unoplatform/uno#16586 (reply in thread) I think it would be helpful if you could share your solution if possible. cc @nickrandolph |
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In commerce example and in default tempates there is aproximately ShellPage->MainPage->SecondPage. So why it works that way, why is shellpage needed, or to rephrase why first loaded page is not in back history ? Thx again. |
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@DomagojJugovich technically Shell isn't required (the Playground sample has different startup options in App.xaml.cs) but it is recommended as it gives you the extendedsplashscreen. Uno.Extensions Navigation is designed to work with routes, so removing them will make navigation difficult. Initial navigation in the application can either be done from ShellModel/ViewModel (like it is today in the template), or you can set IsDefault to true on the RouteMap, or you can override the NavigateAsync method in app.xaml.cs to specify the view or model to navigate to initially. |
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Later on I created ViewMaps and Routes properly. If I use flat hierarchy back navigation works from all pages, it is nested only from Shell onward : private static void RegisterRoutes(IViewRegistry views, IRouteRegistry routes)
{
views.Register(
new ViewMap(ViewModel: typeof(ShellViewModel)),
new ViewMap<MainPage, MainViewModel>(),
new ViewMap<InventuraPage, InventuraViewModel>(),
new ViewMap<PostavkePage, PostavkeViewModel>(),
new ViewMap<NavigationPage, NavigationViewModel>(),
new ViewMap<LokacijePage, LokacijeViewModel>(),
new ViewMap<InventuraOrgjPage, InventuraOrgjViewModel>(),
new ViewMap(View: typeof(InventuraSveStavkePage)),
new ViewMap<InventuraChartsPage, InventuraChartsViewModel>(),
new ViewMap<InventuraNedefiniraneStavkePage, NedefiniraneStavkeViewModel>(),
new ViewMap<InventuraRashodPage, InventuraRashodViewModel>()
//new DataViewMap<SecondPage, SecondViewModel, Entity>()
);
routes.Register(
new RouteMap("", View: views.FindByViewModel<ShellViewModel>(),
Nested: new RouteMap[]
{
new RouteMap("Main", View: views.FindByViewModel<MainViewModel>()),
new RouteMap("Inventura", View: views.FindByViewModel<InventuraViewModel>()),
new RouteMap("Postavke", View: views.FindByViewModel<PostavkeViewModel>()),
new RouteMap("Navigation", View: views.FindByViewModel<NavigationViewModel>()),
new RouteMap("Lokacije", View: views.FindByViewModel<LokacijeViewModel>()),
new RouteMap("Orgj", View: views.FindByViewModel<InventuraOrgjViewModel>()),
new RouteMap("SveStavke", View: views.FindByView<InventuraSveStavkePage>()),
new RouteMap("Charts", View: views.FindByViewModel<InventuraChartsViewModel>()),
new RouteMap("NedefiniraneStavke", View: views.FindByViewModel<NedefiniraneStavkeViewModel>()),
new RouteMap("Rashod", View: views.FindByViewModel<InventuraRashodViewModel>())
}
)
);
}Experimenting gives this : BTW: I took over this app from other developer and I am learning UNO in the process, I did not do any mobile dev before, nor substantial XAML work , our ERP is WinForms, so bear with me. |
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This is not with button clicks but with hardware button, BackRequested event. protected override void OnNavigatedTo(NavigationEventArgs e)
{
#if !WINDOWS
SystemNavigationManager.GetForCurrentView().BackRequested += OnBackRequested;
#endif
}
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
base.OnNavigatedFrom(e);
#if !WINDOWS
SystemNavigationManager.GetForCurrentView().BackRequested -= OnBackRequested;
#endif
}To every Page that is opened after Main. Can it be done with some global listener ? Some Page lifecycle article would be great, plus in context of Navigation. |
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@nickrandolph this.Navigator().NavigateRouteAsync(this, "Navigation", data : inventura);In that moment I get these events on NavigationPage :
And OnNavigatedTo is not called any more. Also I see when navigating from page that DataContext is set to null again. Here is a route configuration to see that NavigationPage, NavigationViewModel is associated corectly in ViewMap and called by route "Navigation". private static void RegisterRoutes(IViewRegistry views, IRouteRegistry routes)
{
views.Register(
new ViewMap(ViewModel: typeof(ShellViewModel)),
new ViewMap<MainPage, MainViewModel>(),
new ViewMap<InventuraPage, InventuraViewModel>(),
new ViewMap<PostavkePage, PostavkeViewModel>(),
new ViewMap<NavigationPage, NavigationViewModel>(),
new ViewMap<LokacijePage, LokacijeViewModel>(),
new ViewMap<InventuraOrgjPage, InventuraOrgjViewModel>(),
new ViewMap(View: typeof(InventuraSveStavkePage)),
new ViewMap<InventuraChartsPage, InventuraChartsViewModel>(),
new ViewMap<InventuraNedefiniraneStavkePage, NedefiniraneStavkeViewModel>(),
new ViewMap<InventuraRashodPage, InventuraRashodViewModel>()
//new DataViewMap<SecondPage, SecondViewModel, Entity>()
);
routes.Register(
new RouteMap("", View: views.FindByViewModel<ShellViewModel>(),
Nested: new RouteMap[]
{
new RouteMap("Main", View: views.FindByViewModel<MainViewModel>()),
new RouteMap("Inventura", View: views.FindByViewModel<InventuraViewModel>()),
new RouteMap("Postavke", View: views.FindByViewModel<PostavkeViewModel>()),
new RouteMap("Navigation", View: views.FindByViewModel<NavigationViewModel>()),
new RouteMap("Lokacije", View: views.FindByViewModel<LokacijeViewModel>()),
new RouteMap("Orgj", View: views.FindByViewModel<InventuraOrgjViewModel>()),
new RouteMap("SveStavke", View: views.FindByView<InventuraSveStavkePage>()),
new RouteMap("Charts", View: views.FindByViewModel<InventuraChartsViewModel>()),
new RouteMap("NedefiniraneStavke", View: views.FindByViewModel<NedefiniraneStavkeViewModel>()),
new RouteMap("Rashod", View: views.FindByViewModel<InventuraRashodViewModel>())
}
)
);
}Please, please help ! |
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This is not unexpected since the shellviewmodel is set by default thanks to the flow of Data context in the visual tree. |
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Thx very much for responding ! Yes in step 4. as I wrote : "4. NavigationPage_DataContextChanged with args.NewValue as NavigationViewModel" which is correct ViewModel. I have no time now, this goes into production in 2 months, and I am far from Bluetooth barcode scanning etc... if (MainWindow.Content is not Frame rootFrame)
{
// Create a Frame to act as the navigation context and navigate to the first page
rootFrame = new Frame();
// Place the frame in the current Window
MainWindow.Content = rootFrame;
}
if (rootFrame.Content == null)
{
// When the navigation stack isn't restored navigate to the first page,
// configuring the new page by passing required information as a navigation
// parameter
rootFrame.Navigate(typeof(MainPage), args.Arguments);
}I will see and report here is this working up to that third page ok I am in the middle of changes , and for rest of app. I have version with Navigation Extension in source control so I can try whatever you suggest also in parallel. Maybe I return to Nav. Extension at the end. I would like to learn but I must get this done, also, no one will care if app works., I didn't saw visual tree so I didn't notice what is happening there. Thx again. |
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Just to confirm , of course it is working when using basic navigation and creating viewmodels myself. |
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Back to App with Nav Ext , test without nesting : routes.Register(
new RouteMap("", View: views.FindByViewModel<ShellViewModel>()),
new RouteMap("Main", View: views.FindByViewModel<MainViewModel>()),
new RouteMap("Inventura", View: views.FindByViewModel<InventuraViewModel>()),
new RouteMap("Postavke", View: views.FindByViewModel<PostavkeViewModel>()),
new RouteMap("Navigation", View: views.FindByViewModel<NavigationViewModel>()),
new RouteMap("Lokacije", View: views.FindByViewModel<LokacijeViewModel>()),
new RouteMap("Orgj", View: views.FindByViewModel<InventuraOrgjViewModel>()),
new RouteMap("SveStavke", View: views.FindByView<InventuraSveStavkePage>()),
new RouteMap("Charts", View: views.FindByViewModel<InventuraChartsViewModel>()),
new RouteMap("NedefiniraneStavke", View: views.FindByViewModel<NedefiniraneStavkeViewModel>()),
new RouteMap("Rashod", View: views.FindByViewModel<InventuraRashodViewModel>())there is no change , on NavigationPage DataContextChanged is called 3 times : ShellViewModel, NULL, NavigationViewModel. |
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I migrated oldour old UNO app, but I created new project/solution with newest templates for UnoSDK / WinUI only, and migrated all may code and files. By that I migrated to Uno SDK, single project and WinUI at once. So it should be clean from inconsistency problems.
All UWP to WinUI tidbits are solved and app runs (first screen loads), Desktop head works, Android works.
So navigation is not working how it worked before, so I looked at tutorials and reworked to :
I have no RegisterRoutes for now, as I see that is not important.
I am trying very simple scenario just to go to other page and back.
I am not able to go back ! ****
I registered event on PostavkePage (think secondPage):
This event fires on android emulator hw button, so that part works. But CanGoBack is false, even if I ignore that and fire NavigateBackAsync nothing happens.
To see how new extension works with navigation I found that best example is commerce app in uno examples so I used that as a guideline.
In App.xml.cs I tried only first line or only second line , it doesn't make a difference , second line I found in commerce example :
//Host = await builder.NavigateAsync();
Host = await MainWindow.InitializeNavigationAsync(async () => builder.Build(), new MainPage());
I watched all techbites, all available documentation, but how navigations works "under the hood" is a mystery to me, will look at the source code of uno navigation extension later.
Also in commerce app I saw how to log debug details of navigation extension so here it is :
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