Apply DI by using unity in WPF application - wpf

Question

I got confused after reading the documentation of Unity framework.
link
I'am writing a WPF application which will search for some devices.
Below my code from my main Window.
As you can see, now i'am still declaring UnitOfWork and DeviceService inside my main Window. I want to replace this code by applying Dependency Injection. At the same time i would also inject my viewmodel inside my main window.
public Window1()
{
InitializeComponent();
UnitOfWork myUnitOfWork = new UnitOfWork();
DeviceService dService = new DeviceService(myUnitOfWork);
_vm = new DeviceViewModel(dService);
this.DataContext = _vm;
_vm.SearchAll();
}
I gave a try in below code but i failed in setting the container. The real question is how should i start? Do i need to completely change the stucture of my program?
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
IUnityContainer container = new UnityContainer();
UnitOfWork myUnitOfWork = new UnitOfWork();
container.RegisterInstance<UnitOfWork>(myUnitOfWork);
Window1 w1 = new Window1();
w1.Show();
}
}
I went trough the suggested tutorial. It is still not clear for me on how i should configure the property injection.
My viewmodel should be injected in the Window 1 class, so i assume that i have to create a dependency property.
private DeviceViewModel viewModel;
[Dependency]
public DeviceViewModel ViewModel
{
get { return viewModel; }
set { this.DataContext = value; }
}
How can i inject my viewmodel into window 1, knowing that DeviceViewModel has dependency on DeviceService and again on UnitOfWork ?
//CONSTRUCTOR
public DeviceViewModel(DeviceService service)
{
Service = service;
SearchCommand = new SearchCommand(this);
}
private UnitOfWork myUnit;
public DeviceService(UnitOfWork unit)
{
myUnit = unit;
}

Answer 1

You need to tell container how to build all the objects needed by other objects, then the container will instantiate whatever is needed when needed.
your property injection is only missing one line:
private DeviceViewModel viewModel;
[Dependency]
public DeviceViewModel ViewModel
{
get { return viewModel; }
set { viewModel = value; this.DataContext = viewModel; }
}
Then on you OnStartup()
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
IUnityContainer container = new UnityContainer();
container.RegisterType<UnitOfWork>();
container.RegisterType<DeviceService>();
container.RegisterType<DeviceViewModel>();
Window1 w1 = container.Resolve<Window1>();
w1.Show();
}
There are different parameters you can use in RegisterType(), so you can control the lifetime and the creation of your objects.

Answer 2

You need to go through this example: http://visualstudiogallery.msdn.microsoft.com/3ab5f02f-0c54-453c-b437-8e8d57eb9942
You are on the right tracks, just you should resolve the window, not new it up.
//instead of Window1 w1 = new Window1();
Window1 w1 = container.Resolve<Window1>();
w1.DataContext = container.Resolve<DeviceViewModel>();
Window1 will no longer need to set its own DataContext