Maui and Regions

[maxxentropy]

I will re-phrase my question to be more specific regarding the use of Regions.

I am creating a simple sample Maui application that loads a module and is capable of navigating between the module's two pages. The Maui application defines a single ContentPage as follows...

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:prism="http://prismlibrary.com"
             x:Class="RegionSample.Views.ContentRegionPage">
  <ContentPage.Content>
    <ContentView prism:RegionManager.RegionName="ContentRegion" />
  </ContentPage.Content>
</ContentPage>

The region the module's views will be loaded into is named "ContentRegion".

Much of the application startup is cribbed from Dan's sample code. I have done my best to sort out the intent of the Region code but I confess there is some of the code that does not make sense to me.

    public static void Configure(PrismAppBuilder builder)
    {
        builder.ConfigureModuleCatalog(ConfigureModuleCatalog);
        builder.RegisterTypes(RegisterTypes)
                .AddGlobalNavigationObserver(context => context.Subscribe(x =>
                {
                    if (x.Type == NavigationRequestType.Navigate)
                        Console.WriteLine($"Navigation: {x.Uri}");
                    else
                        Console.WriteLine($"Navigation: {x.Type}");

                    var status = x.Cancelled ? "Cancelled" : x.Result.Success ? "Success" : "Failed";
                    Console.WriteLine($"Result: {status}");

                    if (status == "Failed" && !string.IsNullOrEmpty(x.Result?.Exception?.Message))
                        Console.Error.WriteLine(x.Result.Exception.Message);
                }))
                .OnAppStart("NavigationPage/ContentRegionPage");
    }

    private static void ConfigureModuleCatalog(IModuleCatalog moduleCatalog)
    {
        moduleCatalog.AddModule<LoginModule.LoginModule>();
    }
    private static void RegisterTypes(IContainerRegistry containerRegistry)
    {
        containerRegistry.RegisterGlobalNavigationObserver();
        containerRegistry.RegisterForNavigation<ContentRegionPage>();
    }

The module code is defined below
public class LoginModule : IModule
{
    public void OnInitialized(IContainerProvider containerProvider)
    {
        var regionManager = containerProvider.Resolve<IRegionManager>();
        regionManager.RegisterViewWithRegion("ContentRegion", nameof(SignInPageView));
    }
    
    public void RegisterTypes(IContainerRegistry containerRegistry)
    {
        containerRegistry
            .RegisterForRegionNavigation<SignInPageView, SignInPageViewModel>()
            .RegisterForRegionNavigation<SignUpPageView, SignUpPageViewModel>();
    }
}

There are two views ( of type ContentView) in this module that basically navigate back and forth with each other for the purpose of the sample. A sign-in page and a sign-up page.

The issue I am running into is that when clicking on the SignUp link Navigation fails. I think it may be because I don't have the Navigation URL correct for the modules page. Below is the Command binding used to navigate to the modules SignUpPageView

    private async Task SignUpAsync()
    {
        var navResult = await _navigationService.NavigateAsync(nameof(SignUpPageView));
    }

I built a sample app that did not use regions, and this navigate command worked fine, so I suspect I have missed something fundamental with the RegionManager version.

The error dumped by the GlobalNavigationObserver is ...
2023-06-12 12:48:03.164785-0400 RegionSample[55329:14482562] Navigation: SignUpPageView
2023-06-12 12:48:03.164978-0400 RegionSample[55329:14482562] Result: Failed
2023-06-12 12:48:03.165101-0400 RegionSample[55329:14482562] No Page has been registered with the provided key

Any thoughts on what might be the issue here?

[maxxentropy]

I was able to resolve the issue by passing an IRegionManager to the view model constructors and using the RequestNavigate method on the IRegionManager interface.

_regionManager.RequestNavigate("ContentRegion", URI);

I am not clear if this is the "correct" way to do navigation rendering a module's view(s) into the applications content area so if anyone has additional insight into this problem please feel free to add on to this discussion.