RegionManager not injecting properly

Question

I'm trying to pass our application that was using the old Prism 4.0 to latest Prism 7.1.0.431

I'm almost done, everything compiles. Dependency injection has been updated to use latest Unity. So everything seems back on track as I see injection working somewhat.

Though I still have a problem with Module loading: region manager cannot be resolved. I think I'm missing something in my initialization code but cannot find any relevant documentation on that. Try to get into all Prism.Wpf samples but could find relevant code.

Injecting the region manager within module is probably not a good practice from the code I'm seeing while search an answer to my issue, but bear with me that right now it's a huge application and would want to avoid changing that as much as possible:

Here is the exception error I'm having:

EXCEPTION: Prism.Modularity.ModuleInitializeException: An exception occurred while initializing module 'AdvancedExportModule'. - The exception message was: Resolution of the dependency failed, type = 'Codex.Modules.AdvancedExport.AdvancedExportModule', name = '(none)'. Exception occurred while: while resolving. Exception is: InvalidOperationException - The current type, Prism.Regions.IRegionManager, is an interface and cannot be constructed. Are you missing a type mapping?

Am I missing something initialization code for the RegionManager to be mapped and injected correctly by Unity?

Here are the code sample, I tried to simply the most of it and hopefully it's enough for you to understand what's wrong... This my App.xaml:

<prism:PrismApplication x:Class="Codex.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:prism="http://prismlibrary.com/">
	<Application.Resources>
		<ResourceDictionary Source="Resources/Merged.xaml"/>
	</Application.Resources>
</prism:PrismApplication>

And in my Code behind App.xaml.cs

    namespace MyNamespace
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Reflection;
    using System.Runtime.InteropServices;
    using System.Windows;
    using System.Windows.Threading;

    using Prism.Ioc;
    using Prism.Logging;
    using Prism.Modularity;
    using Prism.Unity;

    public partial class App : PrismApplication
    {
        private static ILoggerFacade Logger { get; set; }

        public static void Main()
        {
            var application = new App();
            application.InitializeComponent();
            application.Run();
        }

        protected override void OnStartup(StartupEventArgs startupEventArgs)
        {           
            base.OnStartup(startupEventArgs);
        }

        protected override void ConfigureModuleCatalog(IModuleCatalog moduleCatalog)
        {
            var modulesFilePaths = new Dictionary<string, string>();
            modulesFilePaths.Add("Namespace.Modules.Module1.dll", "Namespace.Modules.AdvancedExport.Module1Module");

            var pathToExecutingLibrary = Directory.GetParent(Assembly.GetExecutingAssembly().Location).FullName;

            foreach (KeyValuePair<string, string> moduleFilePath in modulesFilePaths)
            {
                var referenceUri = Path.Combine(pathToExecutingLibrary, moduleFilePath.Key);
                var assembly = Assembly.LoadFrom(referenceUri);
                var type = assembly.GetType(moduleFilePath.Value);

                moduleCatalog.AddModule(
                    new ModuleInfo(type)
                    {
                        ModuleName = type.Name,
                        Ref = referenceUri,
                        InitializationMode = InitializationMode.WhenAvailable
                    });
            }

            moduleCatalog.Initialize();
        }

        protected override void RegisterTypes(IContainerRegistry containerRegistry)
        {
            ConfigureViewModelLocator();
            var containerExtension = CreateContainerExtension();
            containerRegistry.RegisterInstance(containerExtension);

            // These methods have been commented out they are use to register all the types of the application.
            //RegisterSettings(containerRegistry);
            //RegisterServices(containerRegistry);
            //RegisterHandlers(containerRegistry);
            //RegisterWrappers(containerRegistry);

            containerRegistry.RegisterInstance(Dispatcher.CurrentDispatcher);
        }

        protected override Window CreateShell()
        {
            Window mainShell = Container.Resolve<MainShell>();
            return mainShell;
        }
    }
}

Answer 1

You're doing too much and the wrong things in your overrides. Example: RegisterTypes should just register types...

protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
    // this has already been called by the base class: ConfigureViewModelLocator();
    // this has also been called by the base class: var containerExtension = CreateContainerExtension();
    // containerRegistry.RegisterInstance(containerExtension);

    // These methods have been commented out they are use to register all the types of the application.
    //RegisterSettings(containerRegistry);
    //RegisterServices(containerRegistry);
    //RegisterHandlers(containerRegistry);
    //RegisterWrappers(containerRegistry);

    containerRegistry.RegisterInstance(Dispatcher.CurrentDispatcher);
}

You should review the source code to get an understanding of how the overrides are supposed to be called. Essentially, they should not call each other, just do their own work.