Re-implementing WindowManager using ModernUI + Caliburn.Micro combination

Here Caliburn.Micro was successfully combined with ModernUI. But if we want to use multiple windows we also need to re-implement Caliburn's WindowManager to work properly with ModernUI. How can it be done?

UPDATE: (Additional question about IoC-Container/Dependency Injection)

Ok, as I get it: I used a Constructor Injection here:

public class BuildingsViewModel : Conductor<IScreen>

{
    public BuildingsViewModel(IWindowManager _windowManager)
    {
        windowManager = _windowManager;
    }
}

As far as BuildingsViewModel resolved from IoC container, container itself injected ModernWindowManager implementation of IWindowManager interface because of this line in Bootstrapper's Configure() method:

container.Singleton<IWindowManager, ModernWindowManager>();

If I resolving an object instance from container, it injects all needed dependencies. Like a tree.

1) So now I wonder how can I replace this line using an injection(with interface)? _windowManager.ShowWindow(new PopupViewModel());

2) If I want my whole project match DI pattern, all objects instances must be injected into ModernWindowViewModel, that resolves from container first?

3) Is it okay to use Caliburn's SimpleContainer for whole project, or better use mature framework like Castle Windsor? Should I avoid mixing?

UPDATE2:

4) Integrating an IoC container into an existing application requires creating this container first(in Main() method of console app for example), and then all object instanses must grow from it with injected dependencies?

Simply create your own derived WindowManager and override EnsureWindow:

public class ModernWindowManager : WindowManager
{
    protected override Window EnsureWindow(object rootModel, object view, bool isDialog)
    {
        var window = view as ModernWindow;

        if (window == null)
        {
            window = new ModernWindow();
            window.SetValue(View.IsGeneratedProperty, true);
        }

        return window;
    }
}

Any views that you want to use as popups must be based on ModernWindow and must either use a LinkGroupCollection or you must set the ContentSource property of the window, otherwise there will be no content.

You could possibly make this View-First but it works ViewModel-First using the method above.

e.g. to popup my PopupView I did the following

PopupView.xaml

<mui:ModernWindow x:Class="TestModernUI.ViewModels.PopupView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mui="http://firstfloorsoftware.com/ModernUI"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300" ContentSource="/ViewModels/ChildView.xaml">
 </mui:ModernWindow>

PopupViewModel.cs

public class PopupViewModel : Screen
{
    // Blah
}

Code to popup the view from another ViewModel:

public void SomeMethod()
{
    _windowManager.ShowWindow(new PopupViewModel()); // Or use injection etc
}

Don't forget to register ModernWindowManager in place of WindowManager in your container!

e.g. using CM's SimpleContainer

container.Singleton<IWindowManager, ModernWindowManager>();

Obviously the only downside I can see to the above is that you can't seem to put content directly in a ModernWindow, so you have to have two UserControls for every popup!

A workaround would be to change EnsureWindow in ModernWindowManager so that it created a UserControl based on ModernWindow and set the ContentSource to the URI of the view you want to load, this will trigger the content loader and wire up your ViewModel. I'll update if I get a minute to try it.

Update:

Ok, so at the moment it's very hacky, but this could be a starting point for something useful. Basically I'm generating a URI based on the namespace and name of the view.

I'm sure there is a more reliable way of doing this, but for my test project it works:

protected override Window EnsureWindow(object rootModel, object view, bool isDialog)
{
    var window = view as ModernWindow;

    if (window == null)
    {
        window = new ModernWindow();

        // Get the namespace of the view control
        var t = view.GetType();

        var ns = t.Namespace;

        // Subtract the project namespace from the start of the full namespace
        ns = ns.Remove(0, 12);

        // Replace the dots with slashes and add the view name and .xaml
        ns = ns.Replace(".", "/") + "/" + t.Name + ".xaml";

        // Set the content source to the Uri you've made
        window.ContentSource = new Uri(ns, UriKind.Relative);
        window.SetValue(View.IsGeneratedProperty, true);
    }

    return window;
}

My full namespace for my view was TestModernUI.ViewModels.PopupView and the URI generated was /ViewModels/PopupView.xaml which then was loaded and bound via the content loader automagically.

Update 2

FYI here is my Bootstrapper configure method:

protected override void Configure()  
{
    container = new SimpleContainer();

    container.Singleton<IWindowManager, ModernWindowManager>();
    container.Singleton<IEventAggregator, EventAggregator>();
    container.PerRequest<ChildViewModel>();
    container.PerRequest<ModernWindowViewModel>();
    container.PerRequest<IShell, ModernWindowViewModel>();
}

Here I create the container, and register some types.

The CM services such as WindowManager and EventAggregator are both registered against their respective interfaces and as singletons so only 1 instance of each will be available at run time.

The view models are registered as PerRequest which creates a new instance every time you request one from the container - this way you can have the same window popup multiple times without strange behaviour!

These dependencies are injected into the constructor of any objects resolved at run time.

Update 3

In answer to your IoC questions:

1) So now I wonder how can I replace this line using an injection(with interface)? _windowManager.ShowWindow(new PopupViewModel());

Since your viewmodels will now usually need dependencies you need to have some way of injecting them into the instances. If PopupViewModel had several dependencies, you could inject them into the parent class but this would couple the parent viewmodel to PopupViewModel in some way.

There are a couple of other methods you can use to get an instance of PopupViewModel.

Inject it!

If you register PopupViewModel as PerRequest you will get a new instance of it every time you request it. If you only need one popup instance in your viewmodel you can just inject it:

public class MyViewModel 
{
    private PopupViewModel _popup;
    private IWindowManager _windowManager;

    public MyViewModel(PopupViewModel popup, IWindowManager windowManager) 
    {
        _popup = popup;
        _windowManager = windowManager;
    }

    public void ShowPopup()
    {
        _windowManager.ShowPopup(_popup);
    }    
}

The only downside is that the instance will be the same one if you need to use it multiple times in the same viewmodel, though you could inject multiple instances of PopupViewModel if you knew how many you needed at the same time

Use some form of on-demand injection

For dependencies which are required later on you can use on-demand injection such as a factory

I don't think Caliburn or SimpleContainer support factories out of the box, so the alternative is to use IoC.Get<T>. IoC is a static class which lets you access your DI container after instantiation

 public void ShowPopup()
 {
     var popup = IoC.Get<PopupViewModel>();
     _windowManager.ShowWindow(popup);
 }

You need to make sure you have correctly registered the container in your bootstrapper and delegated any calls to CM's IoC methods to the container - IoC.Get<T> calls the bootstrapper's GetInstance and other methods:

Here's an example:

public class AppBootstrapper : BootstrapperBase {
    SimpleContainer container;

    public AppBootstrapper() {
        Initialize();
    }

    protected override void Configure() {
        container = new SimpleContainer();

        container.Singleton<IWindowManager, ModernWindowManager>();
        container.Singleton<IEventAggregator, EventAggregator>();
        container.PerRequest<IShell, ModernWindowViewModel>();

        // Register viewmodels etc here....
    }

    // IoC.Get<T> or IoC.GetInstance(Type type, string key) ....
    protected override object GetInstance(Type service, string key) {
        var instance = container.GetInstance(service, key);
        if (instance != null)
            return instance;

        throw new InvalidOperationException("Could not locate any instances.");
    }

    // IoC.GetAll<T> or IoC.GetAllInstances(Type type) ....
    protected override IEnumerable<object> GetAllInstances(Type service) {
        return container.GetAllInstances(service);
    }

    // IoC.BuildUp(object obj) ....
    protected override void BuildUp(object instance) {
        container.BuildUp(instance);
    }

    protected override void OnStartup(object sender, System.Windows.StartupEventArgs e) {
        DisplayRootViewFor<IShell>();
    }

Castle.Windsor supports factories so that you can Resolve and Release your components and manage their lifetime more explicitly, but I won't go into that here

2) If I want my whole project match DI pattern, all objects instances must be injected into ModernWindowViewModel, that resolves from container first?

You only need to inject the dependencies that the ModernWindowViewModel needs. Anything that is required by children is automatically resolved and injected e.g.:

public class ParentViewModel
{
    private ChildViewModel _child;

    public ParentViewModel(ChildViewModel child)
    {
        _child = child;
    }
}

public class ChildViewModel
{
    private IWindowManager _windowManager;
    private IEventAggregator _eventAggregator;

    public ChildViewModel(IWindowManager windowManager, IEventAggregator eventAggregator) 
    {
        _windowManager = windowManager;
        _eventAggregator = eventAggregator;
    }
}

In the above situation, if you resolve ParentViewModel from the container - the ChildViewModel will get all it's dependencies. You don't need to inject them into the parent.

3) Is it okay to use Caliburn's SimpleContainer for whole project, or better use mature framework like Castle Windsor? Should I avoid mixing?

You can mix, but it might be confusing as they won't work with each other (one container won't know about the other). Just stick with one container, and SimpleContainer is fine - Castle Windsor has a lot more features, but you might never need them (I've only used a few of the advanced features)

4) Integrating an IoC container into an existing application requires creating this container first(in Main() method of console app for example), and then all object instanses must grow from it with injected dependencies?

Yes, you create the container, then you resolve the root component (in 99.9% of applications there is one main component which is called the composition root), and this then builds the full tree.

Here is an example of a bootstrapper for a service based application. I'm using Castle Windsor and I wanted to be able to host the engine in a Windows service or in a WPF application or even in a Console Window (for testing/debug):

// The bootstrapper sets up the container/engine etc
public class Bootstrapper
{
    // Castle Windsor Container
    private readonly IWindsorContainer _container;

    // Service for writing to logs
    private readonly ILogService _logService;

    // Bootstrap the service
    public Bootstrapper()
    {
        _container = new WindsorContainer();

        // Some Castle Windsor features:

        // Add a subresolver for collections, we want all queues to be resolved generically
        _container.Kernel.Resolver.AddSubResolver(new CollectionResolver(_container.Kernel));

        // Add the typed factory facility and wcf facility
        _container.AddFacility<TypedFactoryFacility>();
        _container.AddFacility<WcfFacility>();

        // Winsor uses Installers for registering components
        // Install the core dependencies
        _container.Install(FromAssembly.This());

        // Windsor supports plugins by looking in directories for assemblies which is a nice feature - I use that here:
        // Install any plugins from the plugins directory
        _container.Install(FromAssembly.InDirectory(new AssemblyFilter("plugins", "*.dll")));

        _logService = _container.Resolve<ILogService>();
    }

    /// <summary>
    /// Gets the engine instance after initialisation or returns null if initialisation failed
    /// </summary>
    /// <returns>The active engine instance</returns>
    public IIntegrationEngine GetEngine()
    {
        try
        {
            return _container.Resolve<IIntegrationEngine>();
        }
        catch (Exception ex)
        {
            _logService.Fatal(new Exception("The engine failed to initialise", ex));
        }

        return null;
    }

    // Get an instance of the container (for debugging)
    public IWindsorContainer GetContainer()
    {
        return _container;
    }
}

Once the bootstrapper is created, it sets up the container and registers all services and also plugin dlls. The call to GetEngine starts the application by resolving Engine from the container which creates the full dependency tree.

I did this so that it allows me to create a service or a console version of the application like this:

Service Code:

public partial class IntegrationService : ServiceBase
{
    private readonly Bootstrapper _bootstrapper;

    private IIntegrationEngine _engine;

    public IntegrationService()
    {
        InitializeComponent();

        _bootstrapper = new Bootstrapper();
    }

    protected override void OnStart(string[] args)
    {
        // Resolve the engine which resolves all dependencies
        _engine = _bootstrapper.GetEngine();

        if (_engine == null)
            Stop();
        else
            _engine.Start();
    }

    protected override void OnStop()
    {
        if (_engine != null)
            _engine.Stop();
    }
}

Console App:

public class ConsoleAppExample
{
    private readonly Bootstrapper _bootstrapper;

    private IIntegrationEngine _engine;

    public ConsoleAppExample()
    {
        _bootstrapper = new Bootstrapper();

        // Resolve the engine which resolves all dependencies
        _engine = _bootstrapper.GetEngine();
        _engine.Start();
    }
}

Here's part of the implementation of IIntegrationEngine

public class IntegrationEngine : IIntegrationEngine
{
    private readonly IScheduler _scheduler;
    private readonly ICommsService _commsService;
    private readonly IEngineStateService _engineState;
    private readonly IEnumerable<IEngineComponent> _components;
    private readonly ConfigurationManager _configurationManager;
    private readonly ILogService _logService;

    public IntegrationEngine(ICommsService commsService, IEngineStateService engineState, IEnumerable<IEngineComponent> components,
        ConfigurationManager configurationManager, ILogService logService)
    {
        _commsService = commsService;
        _engineState = engineState;
        _components = components;
        _configurationManager = configurationManager;
        _logService = logService;

        // The comms service needs to be running all the time, so start that up
        commsService.Start();
    }

All of the other components have dependencies, but I don't inject those into the IntegrationEngine - they are handled by the container

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