ReactiveUI¶

ReactiveUI

A model-view-viewmodel (MVVM) framework for WPF, WinForms, WinUI, MAUI, Avalonia and Uno. MVVM keeps screen logic in a view model class that you can test without a UI. Here the Save button turns off while the name is empty.

IObservable<bool> canSave = this.WhenAnyValue(
    x => x.Name, name => !string.IsNullOrWhiteSpace(name));

Save = ReactiveCommand.CreateFromTask(SaveAsync, canSave);

Docs · GitHub

ReactiveUI.Binding

Keeps a view and a view model in step. A source generator writes the binding code when you build, so bindings are safe to trim and to publish with Native AOT. Dispose a binding to stop it.

// The text box shows Name, and typing updates Name.
using var binding = view.Bind(
    viewModel, vm => vm.Name, v => v.NameBox.Text);

Docs · GitHub

ReactiveUI.Validation

Adds validation rules to a view model. Each rule names a property, a check and the message to show when the check fails.

this.ValidationRule(
    vm => vm.Email,
    email => email?.Contains('@') == true,
    "Enter a valid email address.");

Docs · GitHub

Sextant

Navigation that starts from the view model. You open and close pages by naming view models, so you can test navigation without a UI.

// Show the page for DetailsViewModel, then go back.
await viewStack.PushPage<DetailsViewModel>();
await viewStack.PopPage();

Docs · GitHub

Splat

A service locator and logging for every .NET platform. A service locator is one shared place that hands out services. Register a service when your app starts, then ask for it anywhere.

AppLocator.CurrentMutable.RegisterLazySingleton<IWeatherService>(
    () => new WeatherService());

var weather = AppLocator.Current.GetService<IWeatherService>();

Docs · GitHub

ReactiveUI.Primitives

Small, fast streams, ready for Native AOT. Turn events, timers and tasks into streams. Then shape them with operators, methods that take a stream and return a new one. Calm waits for 300 ms of quiet.

using var search = Signal.FromEventPattern(
        h => box.TextChanged += h, h => box.TextChanged -= h)
    .Select(_ => box.Text)
    .Calm(TimeSpan.FromMilliseconds(300))
    .Subscribe(RunSearch);

Docs · GitHub

Refit

Turns a C# interface into a REST client. An attribute on each method describes the request, and Refit writes the code that sends it. Refit takes advantage of System.Text.Json source generation to read JSON without reflection. AppJsonContext is only this example's name for your context class.

public interface IGitHubApi
{
    [Get("/users/{user}")]
    Task<User> GetUserAsync(string user, CancellationToken token);
}

var api = RestService.ForGenerated<IGitHubApi>(
    httpClient, AppJsonContext.Default);

Docs · GitHub

Akavache

Stores objects on the device: a cache, user settings and encrypted secrets. Ask for a key, and Akavache returns the saved copy, or fetches a new one when the copy is missing or has expired.

var news = await CacheDatabase.LocalMachine.GetOrFetchObject(
    "news",
    () => api.GetNewsAsync(),
    DateTimeOffset.Now.AddHours(1));

Docs · GitHub

Punchclock

A queue that limits how many tasks run at once. When a slot frees up, the task with the highest priority runs next.

using var queue = new OperationQueue(maximumConcurrent: 2);

var page = queue.Enqueue(1, () => http.GetStringAsync(pageUrl));
var urgent = queue.Enqueue(10, () => http.GetStringAsync(urgentUrl));
await Task.WhenAll(page, urgent);

Read the guide on GitHub

Fusillade

An HttpClient handler that sends requests in order of importance. Requests the user waits on go first, background work waits, and identical requests share one download.

using var client = new HttpClient(
    NetCache.UserInitiated, disposeHandler: false);

string json = await client.GetStringAsync(url);

Read the guide on GitHub