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View Locator

info

ViewLocator is optional and included in default Avalonia templates. You can use explicit DataTemplates instead.

ViewLocator resolves views for view models in MVVM applications. It implements IDataTemplate to map view model types to view types.

Default Implementation​

The default implementation uses reflection. It replaces "ViewModel" with "View" in the fully-qualified type name and searches for the expected view type.

Example: MyApp.ViewModels.MainViewModel → MyApp.Views.MainView

tip

While the reflection-based approach is the simplest to get started with, consider implementing a custom ViewLocator tailored to your application using one of the alternatives below for better performance, type safety, and ahead-of-time (AOT) compatibility.

public class ViewLocator : IDataTemplate
{
    public Control Build(object data)
    {
        var name = data.GetType().FullName!.Replace("ViewModel", "View");
        var type = Type.GetType(name);

        if (type != null)
        {
            return (Control)Activator.CreateInstance(type)!;
        }
        else
        {
            return new TextBlock { Text = "Not Found: " + name };
        }
    }

    public bool Match(object data)
    {
        return data is ViewModelBase;
    }
}
  • The Match method checks if the data is a ViewModelBase
  • The Build method creates the view instance using reflection, or returns an error TextBlock if the view isn't found

Registration​

Register the ViewLocator in App.axaml:

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="MyApp.App"
             xmlns:local="using:MyApp"
             RequestedThemeVariant="Default">
    <Application.DataTemplates>
        <local:ViewLocator />
    </Application.DataTemplates>

    <Application.Styles>
        <FluentTheme />
    </Application.Styles>
</Application>

Once registered, ViewLocator works automatically:

DataContext = new MainViewModel(); // ViewLocator resolves to MainView

Or with data binding:

<ContentControl Content="{Binding CurrentViewModel}" />

Alternative Implementations​

Pattern Matching​

Type-safe approach without reflection:

public class ViewLocator : IDataTemplate
{
    public Control Build(object data)
    {
        return data switch
        {
            MainViewModel vm => new MainView { DataContext = vm },
            SettingsViewModel vm => new SettingsView { DataContext = vm },
            _ => new TextBlock { Text = $"View not found for {data.GetType().Name}" }
        };
    }

    public bool Match(object data) => data is ViewModelBase;
}
  • Compile-time safety and better performance
  • AOT-compatible
  • IDE refactoring support

DataTemplates in XAML​

Define view-viewmodel mappings declaratively:

<Application.DataTemplates>
    <DataTemplate DataType="{x:Type vm:MainViewModel}">
        <views:MainView />
    </DataTemplate>
    <DataTemplate DataType="{x:Type vm:SettingsViewModel}">
        <views:SettingsView />
    </DataTemplate>
</Application.DataTemplates>

See DataTemplates Collection.

Dependency Injection / IoC​

When using dependency injection (DI), you can integrate ViewLocator with your container to resolve views with their dependencies:

  • Pattern Matching + DI: Combine pattern matching with IServiceProvider.GetRequiredService() for type-safe resolution
  • Factory Registration: Register view factories in your DI container that ViewLocator calls
  • Direct Resolution: Pass service provider to ViewLocator (may still need reflection unless combined with pattern matching or source generators)

Choose based on whether you need to avoid reflection or prefer simpler configuration.

Source Generators​

You can create a custom source generator to generate ViewLocator code at compile time. This provides zero runtime overhead and full AOT compatibility.

For details on creating source generators, see Microsoft's Source Generators documentation.

Third-Party Options​

StaticViewLocator - A NuGet package that automatically discovers and registers views.

ViewLocatorGenerator - An example implementation of a source generator for ViewLocator (not a package, reference implementation).

See Also​