View Locator

Overview

ViewLocator is a component that automatically finds and binds a View to its corresponding ViewModel (presentation logic). It implements the IDataTemplate interface for Avalonia UI and uses IServiceProvider to dynamically resolve views from the dependency container.

How It Works

ViewLocator uses a matching algorithm to find the correct view for a given view model:

Direct Type Match — searches for a view by the ViewModel's full type name
Interface Match — if no direct match is found, searches for views based on the interfaces implemented by the ViewModel
Base Class Hierarchy — if still not found, searches through the base class hierarchy
Fallback — if no view is found, displays a TextBlock with the ViewModel's type name for debugging

The locator only matches the objects implementing IViewModel:

public bool Match(object? data)
{
    return data is IViewModel;
}

Setup

ViewLocator is automatically registered by the framework when you use AsvApplication as your App base class. It is added to the application's DataTemplates collection during initialization.

Registering Views

Use the ViewLocator builder in your mixin to register a view for a view model:

builder.ViewLocator.RegisterViewFor<MyFeatureViewModel, MyFeatureView>();

This registers the view as a keyed transient service in the IServiceCollection container.

Example

Basic View Registration

// ViewModel
public class SearchBoxViewModel : RoutableViewModel
{
    public string SearchText { get; set; }
}

// View
public partial class SearchBoxView : UserControl
{
    public SearchBoxView()
    {
        InitializeComponent();
    }
}

// Registration (in your mixin):
builder.ViewLocator.RegisterViewFor<SearchBoxViewModel, SearchBoxView>();

Troubleshooting

View Not Found

If a view cannot be found, a TextBlock with the view model's type name will be displayed. This helps identify missing view registrations during development.

Make sure to:

Register the view for your view model via builder.ViewLocator.RegisterViewFor<TViewModel, TView>()
Verify your view is a Control subclass

Last modified: 20 April 2026