# IViewResolver

As we have already wrote when we spoke about [Runtime Conventions](/release-2/presentation/conventions/runtime-conventions.md) 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](https://github.com/RadicalFx/documentation/tree/3593d0c5b04875dd1fb6be74908fc5cea4ac1a8d/messaging/message-broker.md) 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;


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.radicalframework.com/release-2/presentation/iview-resolver.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.