IViewResolver

As we have already wrote when we spoke about Runtime Conventions Radical utilizes by default a view first approach, that even if is completely replaceable with a ViewModel first approach, must be understood.
The main and only entry point used to resolve views is IViewResolver interface whose role is to resolve a view instance given a view type:
IViewResolver service; //injected by the IoC engine
var viewUsingGenerics = service.GetView<SampleView>();
var viewUsingType = service.GetView( typeof( SampleView ) );
At runtime when the GetView method is called the default built-in view resolver does the following things:
1.goes to the IoC container and resolves an instance of the requested view type;
2.if the view already has a DataContext it assumes that the view is a singleton and has been already resolved once and immediately returns the resolved view;
3.Otherwise, using the conventions:
4.Using the ResolveViewModelType convention determines the type of the associated ViewModel;
5.Resolves, via the container, the ViewModel;
6.Set the relation View – ViewModel;
7.Set the ViewModel as the DataContext of the View;
8.Attaches to the View the required behaviors;
9.Exposes services registered to be exposed as resources in the View
10.Returns the view to the caller;
How to use the IViewResolver in our application
The typical usage of the view resolver in the application is to open/show another view, the easiest way is to declare a dependency on the resolver in our component:
class SampleViewModel
{
    readonly IViewResolver service;
​
    public SampleViewModel( IViewResolver service )
    {
        this.service = service;
    }
​
    public void ShowAView()
    {
        var myView = this.service.GetView<MyView>();
        myView.Show();
    }
}
We are using the simplest possible approach in order to keep the sample complexity really low.
Notes
In the above sample we are violating the MVVM pattern because we are dealing with a view within the ViewModel, in the chapter related to the MessageBroker we’ll see how to avoid this mix.
A view does not require a view model to work properly, the IViewResolver can resolve views that don't have view models;
Last modified 1yr ago