Navigation between lazy loaded modules with Prism and WPF

Question

Hello I'm trying to setup an architecture where only one module gets booted when the app is launched. Then I'd like to lazy load other modules based on the user's actions.

To achieve this in my app.xaml.cs I have one module loaded at bootstrap time (MainModule), and an other has InitializationMode = InitializationMode.OnDemand

    protected override void ConfigureModuleCatalog(IModuleCatalog moduleCatalog)
    {

        Type BlipModuleType = typeof(BlipModule);
        moduleCatalog.AddModule(new ModuleInfo()
        {
            ModuleName = BlipModuleType.Name,
            ModuleType = BlipModuleType.AssemblyQualifiedName,
            InitializationMode = InitializationMode.OnDemand
        });

        moduleCatalog.AddModule<MainModule>();
    }

then my main module, which displays the view correctly, has a single view registered to the only region available:

    public class MainModule : IModule
    {

        private readonly IRegionManager _regionManager;

        public MainModule(IRegionManager regionManager)
        {
            _regionManager = regionManager;
        }
        public void OnInitialized(IContainerProvider containerProvider)
        {
            _regionManager.RegisterViewWithRegion(RegionNames.ContentRegion, typeof(ViewA));
        }

        public void RegisterTypes(IContainerRegistry containerRegistry)
        {
        }
    }

The lazy loaded module has the same structure, registering a different view (which works properly if i decide to use it as my main module)

    public class BlipModule : IModule
    {
        private readonly IRegionManager _regionManager;

        public BlipModule(IRegionManager regionManager)
        {
            _regionManager = regionManager;

        }
        public void OnInitialized(IContainerProvider containerProvider)
        {
            _regionManager.RegisterViewWithRegion(RegionNames.ContentRegion, typeof(ViewB));

        }

        public void RegisterTypes(IContainerRegistry containerRegistry)
        {
        }
    }

finally I have a Command in the viewmodel of my MainModule ViewA, that is supposed to load the new module and navigate to it.

public class ViewAViewModel : BindableBase
{
    const string BlipModuleName = "BlipModule";

    public ReactiveCommand ChangeRoute { get; set; } = new ReactiveCommand();

    public ViewAViewModel(IRegionManager regionManager, IModuleManager moduleManager)
    {
        ChangeRoute.Subscribe(res =>
        {
            moduleManager.LoadModule(BlipModuleName);
        });

        moduleManager.LoadModuleCompleted += (s, e) =>
        {
            if (e.ModuleInfo.ModuleName == BlipModuleName)
            {
                regionManager.RequestNavigate(RegionNames.ContentRegion, new Uri(BlipModuleName, UriKind.Relative));
            }
        };
    }

}

The viewB of the BlipModule is actually loaded (I get a hit if I set a breakpoint in the view's constructor), but instead of the view I get a white page with "System.Object" inside of it. Any idea? thanks!

score 0 · Accepted Answer · answered Feb 03 '20 at 07:45

0

You want to RegisterForNavigation instead of RegisterViewWithRegion.

answered Feb 03 '20 at 07:45

Haukinger

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I tried to use ```RegisterForNavigation``` but with no luck with my code. But you put me on the right path, the other error i made was to request a navigation to a module instead to a view. So in my viewModel i changed ```regionManager.RequestNavigate(RegionNames.ContentRegion, new Uri("BlipModule", UriKind.Relative));``` to ```regionManager.RequestNavigate(RegionNames.ContentRegion, new Uri("BlipView", UriKind.Relative));``` and it did the trick. Thanks! – nomadev Feb 03 '20 at 09:33
The name's arbitrary, so you _could_ use a module name for a view, actually. Just pass the desired name when registering the view to override the default name, i.e. the name of the view type. – Haukinger Feb 03 '20 at 11:35
Yes sure, but I meant that I was actually using the module's name for the navigation and not the view name (apart from the content of the strings that I chose for representing models and views). – nomadev Feb 03 '20 at 11:55

Navigation between lazy loaded modules with Prism and WPF

1 Answers1