Using Prism, I've got a INFRASTRUCTURE project, where I've got a view with two regions:
ContentRegion
SidebarRegion
There's no problem in SidebarRegion, because this is a especif view of this project. But ContentRegion is different, I've got another modules like ModuleA, ModuleB, and these one contain the view which must be show in ContentRegion.
I mean, the INFRASTRUCTURE PROJECT contains the generic view. And the others module contains a view which must be showed in ContentRegion
I'm using Prism and UNITY. Can you orient me about how can I do this? I guess I need to register the views but I'm lost.
You should be able to pass the Region Manager and Unity container to the modules through the constructor. Then you can use those to register your views in the Initialize method, like so:
public class ModuleA : IModule
{
private readonly IUnityContainer _container;
private readonly IRegionManager _regionManager;
public ModuleA(IUnityContainer container, IRegionManager regionManager)
{
_container = container;
_regionManager = regionManager;
}
public void Initialize()
{
_regionManager.RegisterViewWithRegion("ContentRegion",
() => _container.Resolve<NameOfYourView>());
}
}
And, of course, you have to make sure the modules are loaded properly, but I'm assuming that is done already.
Related
I want to take advantage of dependency injection in my Xamarin project but can't get constructor injection to work in C# classes behind XAML views. Is there any way to do it ?
I've seen guides how to setup dependency injections in View Models, to later use them as repositories but that doesn't work for me.
So far I tried Ninject and Unity.
Code:
This is the service I want to use inside of my PCL project:
public class MyService : IMyService
{
public void Add(string myNote)
{
//Add Note logic
}
}
Interface:
public interface IMyService
{
void Add(string myNote);
}
Unity setup in App.Xaml:
public App ()
{
InitializeComponent();
var unityContainer = new UnityContainer();
unityContainer.RegisterType<IMyService, MyService>();
var unityServiceLocator = new UnityServiceLocator(unityContainer);
ServiceLocator.SetLocatorProvider(() => unityServiceLocator);
MainPage = new MainMasterMenu(); //<-- feel that I'm missing something here as I shouldn't be creating class instances with DI, right ?
}
Usage that I'd like to see. This is .CS file behind a XAML starting page:
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainMasterMenu : MasterDetailPage
{
private IMyService _myService;
public MainMasterMenu(IMyService myService)
{
_myService = myService
}
private void SomeFormControlClickEvent(object sender, ItemChangedEventArgs e)
{
_myService.Add("hi");
}
}
For that simple example creating the MainMasterMenu directly would be no issue, but you would have to pass the reference to your service
MainPage = new MainMasterMenu(unityContainer.Resolve<IMyService>());
But this would mean that you'll have to change that line every time the constructor of MainMasterMenu changes. You could circumvent this by registering the MainMasterMenu, too.
unityContainer.RegisterType<MainMasterMenu>();
...
MainPage = unityContainer.Resolve<MainMasterPage>();
Anyway, anytime you want to navigate to another page, which needs any dependency registered with unity, you'll have to make sure to resolve its dependencies properly, which requires (at least indirect) access to the unity container. You could pass a wrapper that encapsules the access to unity
interface IPageResolver
{
T ResolvePage<T>()
where T : Page;
}
and then implement that resolver with unity
public class UnityPageResolver
{
private IUnityContainer unityContainer;
public UnityPageResolver(IUnityContainer unityContainer)
{
this.unityContainer = unityContainer;
}
public T ResolvePage<T>()
where T : Page // do we need this restriction here?
{
return unityContainer.Resolve<T>();
}
}
This gets registered with unity
unityContainer.RegisterInstance<IUnityContainer>(this);
unityContainer.RegisterType<IPageResolver, UnityPageResolver>();
But you should have a look at the Prism library (see here) that solves many of the issues (e.g. it provides an INavigationService that lets you navigate to other pages without caring about the dependencies and it provides facilities to resolve viewmodels automatically, including dependencies).
I have composite application with toolbar and I want to make my modules possible to add some buttons to toolbar. As I have understood, a RegionManager should be used to provide this possibility.
I wrote a code like this:
public class MyModule : IModule
{
private readonly IUnityContainer _container;
public MyModule(IUnityContainer Container) { _container = Container; }
public void Initialize()
{
var regionManager = _container.Resolve<RegionManager>();
regionManager.RegisterViewWithRegion("MainToolbar",
() => new Button
{
Content = "My Button",
Command = new DelegateCommand(/* */)
});
}
}
But it seems like creating a buttons from code, especially inside of Module class is not a good idea, according the MVVM pattern. And the second problem is that the button is being created before other modules would be initialized, so I can't refer to services registred by other modules.
What exactly I'm doing wrong? What is a propper way to collect actions from multiple modules into one toolbar?
Your idea is correct, just swap out the button for a view that contains a button. Then make the toolbar a region and inject the "button"-view into the "toolbar"-region.
If your module depends on services that come from other modules, make your module dependent on those modules, so that prism makes sure that the services are initialized first:
[ModuleDependency("ServiceModule")]
public class ModuleA : IModule
{
...
}
public class ServiceModule : IModule
{
...
}
I have just one module in Prism application. Let this module have name ModuleA and application name is "CoolAppl". This application is cool and it works really okay in production. Once some guy would like to add new button, for example "Delete Person", to this application "CoolAppl".
My question is can I or another guy from another city add new button "Delete Person" to ModuleA of application "CoolAppl" without recompilation any module just by adding dll with necessary button Delete Person?
If it is possible, please, provide me direction where I should dig/search:).
I am using a such mechanism of navigation:
Uri wholeView = new Uri("ModuleA", UriKind.Relative);
regionManager.RequestNavigate(RegionNames.TheBottomRegion, wholeView);
var currentView = regionManager.Regions[RegionNames.TheWholeRegion].Views.ElementAt(0);
regionManager.Regions[RegionNames.TheWholeRegion].Remove(currentView);
And class to identificate modules looks like that:
public class ModuleAModule : ModuleBase, IModule
{
private readonly IRegionManager _regionManager;
private readonly IUnityContainer _container;
public ModuleAModule(IUnityContainer container, IRegionManager regionManager)
: base(container, regionManager)
{
_regionManager = regionManager;
_container = container;
}
protected override void InitializeModule()
{
RegionManager.RegisterViewWithRegion(RegionNames.TheWholeRegion, typeof(LoginControl));
}
protected override void RegisterTypes()
{
Container.RegisterType<IViewModel, MyViewModel>();
Container.RegisterTypeForNavigation<MySuperControl>();
}
}
If no recompilation means "not recompile everything", then you can just recompile ModuleA. If it means "recompile nothing at all", you're out of luck.
If the new button doesn't need to be in ModuleA, you can create a new ModuleB without either recompiling CoolAppl or ModuleA (but you need to compile ModuleB).
You might have put a plugin-system in place, though, that loads the buttons from plugins, then you can add another plugin for the new button.
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
I am using Prism + Unity in a wpf application using MVVM. I am a beginner with Prism and Unity.
I want to be able to close the current view. The various solutions and articles I've read state that the best way to do this is from the view model. But the view model needs a region manager object in order to close the view. Ok, so let's set up constructor injection. Never tried this before but there are plenty of questions on SO that deal with this.
Let me start with explaining how things are wired together. I have a bootstrapper class that handles the registering of types and instances.
Here is how my view and view model is registered:
container.RegisterType<IViewModel, ViewAccountsViewModel>(new InjectionConstructor(new ResolvedParameter(typeof(RegionManager))));
container.RegisterType<ViewAccountsView>();
Here is the module for the view accounts view:
public class ViewAccountsModule : IModule
{
private readonly IRegionManager regionManager;
private readonly IUnityContainer container;
public ViewAccountsModule(IUnityContainer container, IRegionManager regionManager)
{
this.container = container;
this.regionManager = regionManager;
}
/// <summary>
///
/// </summary>
public void Initialize()
{
regionManager.RegisterViewWithRegion("MainRegion", () => this.container.Resolve<ViewAccountsView>());
}
}
In my ViewAccountsView.xaml, I am setting the data context like so:
<Grid.DataContext>
<vm:ViewAccountsViewModel/>
</Grid.DataContext>
And my view model constructor:
[InjectionConstructor]
public ViewAccountsViewModel(IRegionManager regionManager)
{
if (regionManager == null) throw new ArgumentNullException("regionManager");
this.regionManager = regionManager;
}
When I compile the solution, I receive an error that the type "ViewAccountsViewModel" does not include any accessible constructors. If I add a default constructor to my view model, the view displays but I cannot remove the view from the region. I get an argument null exception.
Here is the code for removing the view:
regionManager.Regions["MainRegion"].Remove(regionManager.Regions["MainRegion"].GetView("ViewAccountsView"));
I am still very much a beginner with IoC and DI. Is there something I have missed?
Unity will handle injecting all dependencies it knows about for you. By default, Unity will call the constructor with the most parameters. You usually use InjectionConstructor to either tell Unity to choose a different constructor when it creates the objects for you, or if you want to pass it custom parameters.
Registration:
container.RegisterType<IViewModel, ViewAccountsViewModel>();
// If you plan to have multiple IViewModels, it will need to have a name
// container.RegisterType<IViewModel, ViewAccountsViewModel>("ViewAccountsViewModelName");
container.RegisterType<ViewAccountsView>();
ViewModel:
// If you decide later you need other dependencies like IUnityContainer, you can just set
// it in your constructor and Unity will give it to you automagically through the power
// of Dependency Injection
// public ViewAccountsViewModel(IRegionManager regionManager, IUnityContainer unityContainer)
public ViewAccountsViewModel(IRegionManager regionManager)
{
this.regionManager = regionManager;
}
View Code Behind:
// If you have a named IViewModel
// public ViewAccountsView([Dependency("ViewAccountsViewModelName")]IViewModel viewModel)
public ViewAccountsView(IViewModel viewModel)
{
this.InitializeComponent();
this.DataContext = viewModel;
}