ViewLocator.Generator 2025.8.4.737-manual

ViewLocator.Generator

A C# source generator that automatically implements static view locator for Avalonia without using reflection.

Originally from wieslawsoltes/StaticViewLocator

Usage

Add NuGet package references to your project:

<PackageReference Include="ViewLocator.Generator" Version="0.0.1">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
</PackageReference>
<PackageReference Include="ViewLocator.Generator.Common" Version="0.0.1" />

Annotate view locator class with [GenerateViewLocator] attribute, make class partial and implement Build using s_views dictionary to retrieve views for data objects.

using ViewLocator.Generator.Common;

[GenerateViewLocator]
public partial class ViewLocator : IDataTemplate
{
    public Control? Build(object? data)
    {
        if (data is null)
        {
            return null;
        }

        var type = data.GetType();

        if (s_views.TryGetValue(type, out var func))
        {
            return func.Invoke();
        }

        throw new Exception($"Unable to create view for type: {type}");
    }

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

Source generator will generate the s_views dictionary similar to below code using convention based on ViewModel suffix for view models substituted to View suffix.

public partial class ViewLocator
{
	private static Dictionary<Type, Func<Control>> s_views = new()
	{
		[typeof(GenerateViewLocatorDemo.ViewModels.MainWindowViewModel)] = () => new GenerateViewLocatorDemo.Views.MainWindow(),
		[typeof(GenerateViewLocatorDemo.ViewModels.TestViewModel)] = () => new GenerateViewLocatorDemo.Views.TestView(),
	};
}

Configuration Options

The GenerateViewLocator attribute supports several properties to customize the view location behavior:

ViewToViewModelNamespaceRule

Transforms view namespaces to view model namespaces using a mapping rule.

Format: "ViewNamespace -> ViewModelNamespace"

[GenerateViewLocator(ViewToViewModelNamespaceRule = "Views -> ViewModels")]
public partial class ViewLocator : IDataTemplate
{
    // Implementation...
}

Example transformations:

• MyApp.Views.UserView → MyApp.ViewModels.UserViewModel
• MyApp.Views.Products.ProductView → MyApp.ViewModels.Products.ProductViewModel

ViewToViewModelSuffixRule

Transforms view suffixes to view model suffixes using a mapping rule.

Format: "ViewSuffix -> ViewModelSuffix"

[GenerateViewLocator(ViewToViewModelSuffixRule = "Page -> PageViewModel")]
public partial class ViewLocator : IDataTemplate
{
    // Implementation...
}

Example transformations:

• UserPage → UserPageViewModel
• ProductPage → ProductPageViewModel

IncludeNamespaces

Only includes ViewModels from the specified namespaces. This is useful when you want to limit view location to specific parts of your application.

[GenerateViewLocator(IncludeNamespaces = new[] { "MyApp.ViewModels", "SharedLib.ViewModels" })]
public partial class ViewLocator : IDataTemplate
{
    // Implementation...
}

ExcludeNamespaces

Excludes ViewModels from the specified namespaces. This is particularly useful for excluding framework or third-party ViewModels.

[GenerateViewLocator(ExcludeNamespaces = new[] { "Avalonia", "System" })]
public partial class ViewLocator : IDataTemplate
{
    // Implementation...
}

Combined Configuration

You can combine multiple properties for complex scenarios:

[GenerateViewLocator(
    ViewToViewModelNamespaceRule = "Views -> ViewModels",
    ViewToViewModelSuffixRule = "View -> ViewModel",
    ExcludeNamespaces = new[] { "Avalonia", "System" },
    IncludeNamespaces = new[] { "MyApp" }
)]
public partial class ViewLocator : IDataTemplate
{
    // Implementation...
}

Default Behavior

When no configuration is specified, the default behavior is:

• Namespace transformation: ViewModels → Views
• Suffix transformation: ViewModel → View (with special handling for WindowViewModel → Window)
• Include all: All accessible ViewModels are included (except when explicitly excluded)

Examples

See the Examples directory for comprehensive examples demonstrating each configuration option.

Common Use Cases

1. Standard MVVM with Framework Exclusion

[GenerateViewLocator(ExcludeNamespaces = new[] { "Avalonia" })]

2. Custom Naming Convention

[GenerateViewLocator(
    ViewToViewModelNamespaceRule = "UI -> Business.ViewModels",
    ViewToViewModelSuffixRule = "Control -> ControlViewModel"
)]

3. Multi-Project Architecture

[GenerateViewLocator(
    IncludeNamespaces = new[] { "MyApp.Core.ViewModels", "MyApp.Modules.ViewModels" },
    ExcludeNamespaces = new[] { "ThirdParty" }
)]

License

ViewLocator.Generator is licensed under the MIT license. See LICENSE file for details.