Utilizing Splat with MS.Extensions.DependencyInjection

[Jeremy-Code-F]

Hi,

I'm trying to setup Dependency injection with Splat since it is already installed with Avalonia. I've been trying to follow this but hit some issues.

My App.axaml.cs looks like

public partial class App : Application
    {
        public IServiceProvider Container { get; private set; }
        public override void Initialize()
        {
            AvaloniaXamlLoader.Load(this);
        }

        public override void OnFrameworkInitializationCompleted()
        {
            using (IHost host = Host.CreateDefaultBuilder()
                       .ConfigureServices((_, services) =>
                       {
                           services.UseMicrosoftDependencyResolver();
                           var resolver = Locator.CurrentMutable;
                           resolver.InitializeSplat();
                           resolver.InitializeReactiveUI();
                           
                           services.AddHttpClient();
                           services.AddTransient<IPsHttpRequestService, PsHttpRequestService>(); 
                           
                           services.AddTransient<MainWindow>();
                           services.AddTransient<MainWindowViewModel>();
                       })
                       .Build())
            {
                // using (var scope = host.Services.CreateScope())
                // {
                    Container = host.Services;
                    Container.UseMicrosoftDependencyResolver();
                    if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
                    {
                        desktop.MainWindow =
                            Locator.Current.GetService<MainWindow>(); // host.Services.GetRequiredService<MainWindow>();
                        // desktop.MainWindow = scope.ServiceProvider.GetRequiredService<MainWindow>();
                        // desktop.MainWindow = new MainWindow
                        // {
                        //     DataContext = new MainWindowViewModel(),
                        // };
                    }

                    base.OnFrameworkInitializationCompleted();
                    
                // }
                
            }
        }
    }

That works fine and the application window opens and seems to work, my issue comes in at a button that tries to use an injected IHttpClientFactory...

private readonly IHttpClientFactory _httpClientFactory;
    public SelectedRequestView(IHttpClientFactory clientFactory)
    {
        _httpClientFactory = clientFactory;
        InitializeComponent();
    }

    public SelectedRequestView()
    {
        _httpClientFactory = (IHttpClientFactory?)Locator.Current.GetService(typeof(IHttpClientFactory));
       InitializeComponent(); 
    }

    private void InitializeComponent()
    {
        AvaloniaXamlLoader.Load(this);
    }

    private void Button_OnClick(object? sender, RoutedEventArgs e)
    {
        var vm = (PsHttpRequestViewModel)((Button)sender).DataContext;
        HttpClient httpClient = _httpClientFactory.CreateClient();
        vm.ResponseMessage = httpClient.GetAsync(vm.Request.Url).Result;
        vm.ResponseMessage.Content.ReadAsStringAsync();
    }

When the Button_OnClick function runs I get an error message,

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'IServiceProvider'.
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ThrowHelper.ThrowObjectDisposedException()
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateScope()
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.CreateScope()
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandlerEntry(String name)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass14_0.<.ctor>b__1()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandler(String name)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateClient(String name)
   at System.Net.Http.HttpClientFactoryExtensions.CreateClient(IHttpClientFactory factory)
   at PostSharp.Views.SelectedRequestView.Button_OnClick(Object sender, RoutedEventArgs e) in C:\Users\user\RiderProjects\PostSharp\PostSharp\Views\SelectedRequestView.axaml.cs:line 35
   at Avalonia.Interactivity.Interactive.<AddHandler>g__InvokeAdapter|4_0[TEventArgs](Delegate baseHandler, Object sender, RoutedEventArgs args) in /_/src/Avalonia.Interactivity/Interactive.cs:line 62
   at Avalonia.Interactivity.Interactive.<>c__4`1.<AddHandler>b__4_1(Delegate baseHandler, Object sender, RoutedEventArgs args) in /_/src/Avalonia.Interactivity/Interactive.cs:line 68
   at Avalonia.Interactivity.EventRoute.RaiseEventImpl(RoutedEventArgs e) in /_/src/Avalonia.Interactivity/EventRoute.cs:line 167
   at Avalonia.Interactivity.EventRoute.RaiseEvent(IInteractive source, RoutedEventArgs e) in /_/src/Avalonia.Interactivity/EventRoute.cs:line 101
   at Avalonia.Interactivity.Interactive.RaiseEvent(RoutedEventArgs e) in /_/src/Avalonia.Interactivity/Interactive.cs:line 122
   at Avalonia.Controls.Button.OnClick() in /_/src/Avalonia.Controls/Button.cs:line 312
   at Avalonia.Controls.Button.OnPointerReleased(PointerReleasedEventArgs e) in /_/src/Avalonia.Controls/Button.cs:line 357
   at Avalonia.Input.InputElement.<>c.<.cctor>b__32_9(InputElement x, PointerReleasedEventArgs e) in /_/src/Avalonia.Input/InputElement.cs:line 223
   at Avalonia.Interactivity.RoutedEvent`1.<>c__DisplayClass2_0`1.<AddClassHandler>g__Adapter|0(Object sender, RoutedEventArgs e) in /_/src/Avalonia.Interactivity/RoutedEvent.cs:line 143
   at Avalonia.Interactivity.RoutedEvent.<>c__DisplayClass23_0.<AddClassHandler>b__0(ValueTuple`2 args) in /_/src/Avalonia.Interactivity/RoutedEvent.cs:line 92
   at System.Reactive.AnonymousObserver`1.OnNextCore(T value) in /_/Rx.NET/Source/src/System.Reactive/AnonymousObserver.cs:line 67
   at System.Reactive.ObserverBase`1.OnNext(T value) in /_/Rx.NET/Source/src/System.Reactive/ObserverBase.cs:line 34
   at System.Reactive.Subjects.Subject`1.OnNext(T value) in /_/Rx.NET/Source/src/System.Reactive/Subjects/Subject.cs:line 147
   at Avalonia.Interactivity.RoutedEvent.InvokeRaised(Object sender, RoutedEventArgs e) in /_/src/Avalonia.Interactivity/RoutedEvent.cs:line 99
   at Avalonia.Interactivity.EventRoute.RaiseEventImpl(RoutedEventArgs e) in /_/src/Avalonia.Interactivity/EventRoute.cs:line 148
   at Avalonia.Interactivity.EventRoute.RaiseEvent(IInteractive source, RoutedEventArgs e) in /_/src/Avalonia.Interactivity/EventRoute.cs:line 101
   at Avalonia.Interactivity.Interactive.RaiseEvent(RoutedEventArgs e) in /_/src/Avalonia.Interactivity/Interactive.cs:line 122
   at Avalonia.Input.MouseDevice.MouseUp(IMouseDevice device, UInt64 timestamp, IInputRoot root, Point p, PointerPointProperties props, KeyModifiers inputModifiers) in /_/src/Avalonia.Input/MouseDevice.cs:line 311
   at Avalonia.Input.MouseDevice.ProcessRawEvent(RawPointerEventArgs e) in /_/src/Avalonia.Input/MouseDevice.cs:line 177
   at Avalonia.Input.MouseDevice.ProcessRawEvent(RawInputEventArgs e) in /_/src/Avalonia.Input/MouseDevice.cs:line 90
   at Avalonia.Input.InputManager.ProcessInput(RawInputEventArgs e) in /_/src/Avalonia.Input/InputManager.cs:line 35
   at Avalonia.Controls.TopLevel.HandleInput(RawInputEventArgs e) in /_/src/Avalonia.Controls/TopLevel.cs:line 504
   at Avalonia.Win32.WindowImpl.AppWndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam) in /_/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs:line 520
   at Avalonia.Win32.WindowImpl.WndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam) in /_/src/Windows/Avalonia.Win32/WindowImpl.WndProc.cs:line 30
   at Avalonia.Win32.Interop.UnmanagedMethods.DispatchMessage(MSG& lpmsg)
   at Avalonia.Win32.Win32Platform.RunLoop(CancellationToken cancellationToken) in /_/src/Windows/Avalonia.Win32/Win32Platform.cs:line 205
   at Avalonia.Threading.Dispatcher.MainLoop(CancellationToken cancellationToken) in /_/src/Avalonia.Base/Threading/Dispatcher.cs:line 65
   at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(String[] args) in /_/src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs:line 120
   at Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime[T](T builder, String[] args, ShutdownMode shutdownMode) in /_/src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs:line 209
   at PostSharp.Program.Main(String[] args) in C:\Users\user\RiderProjects\PostSharp\PostSharp\Program.cs:line 13

any idea what I am missing in this setup?

Thanks

[maxkatz6]

It seems exception is pretty clear. Why would you need to dispose host before using it?

[Jeremy-Code-F]

I don't think I would want to dispose host before using it, I think my problem comes from a misunderstanding of the lifetime for host it seems to me like I have the setup for host in the wrong place and it gets disposed and then the app lifetime starts. So when my button click event fires it gets that error rightfully. But I'm not sure where else to setup Host so that it wouldn't get disposed and is available during the app runtime, hopefully that makes sense, thanks!

[maxkatz6]

You can initialize host in the OnFrameworkInitializationCompleted but dispose it in the end of Program.Main method.

[Jeremy-Code-F]

Thanks! Got this to work

//app.xaml.cs

public partial class App : Application
    {
        public IServiceProvider Container { get; private set; }
        public IHost host { get; set; }
        public override void Initialize()
        {
            AvaloniaXamlLoader.Load(this);
        }

        public override void OnFrameworkInitializationCompleted()
        {
            host = Host.CreateDefaultBuilder()
                .ConfigureServices((_, services) =>
                {
                    services.UseMicrosoftDependencyResolver();
                    var resolver = Locator.CurrentMutable;
                    resolver.InitializeSplat();
                    resolver.InitializeReactiveUI();

                    services.AddHttpClient();
                    services.AddTransient<IPsHttpRequestService, PsHttpRequestService>();

                    services.AddTransient<MainWindow>();
                    services.AddTransient<MainWindowViewModel>();
                })
                .Build();
                    Container = host.Services;
                    Container.UseMicrosoftDependencyResolver();
                    if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
                    {
                        desktop.MainWindow =
                            Locator.Current.GetService<MainWindow>(); // host.Services.GetRequiredService<MainWindow>();
                    }

                    base.OnFrameworkInitializationCompleted();
                
        }
    }

// program.cs

class Program
    {
        // Initialization code. Don't use any Avalonia, third-party APIs or any
        // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
        // yet and stuff might break.
        [STAThread]
        public static void Main(string[] args)
        {
            var appBuilder = BuildAvaloniaApp();
            var app = (App)appBuilder.Instance;
            appBuilder.StartWithClassicDesktopLifetime(args) ;
            app.host.Dispose();
            
        }

        // Avalonia configuration, don't remove; also used by visual designer.
        public static AppBuilder BuildAvaloniaApp()
            => AppBuilder.Configure<App>()
                .UsePlatformDetect()
                .LogToTrace()
                .UseReactiveUI();
    }