帶ASP.Net Core 2.0 IOptions的簡單注入器快照注入

Question

我正在嘗試在錯誤＃429中提出的建議，並且遇到了他在該位置報告的錯誤，但是從沒有提供堆棧跟蹤。 我還閱讀並使用了直到最近的有關不使用IOptions和相關類的指南。 當我們在Azure中運行某些東西時，確實需要IOptionsSnapshot ，並且當我們達到極限時，需要能夠即時打開/關閉選項，並且重啟服務不是選項，因為它最多需要5個最初需要幾分鍾，這是由於我們需要一些第三方產品。

這是我們設置的內容：

• 簡單注射器4.3.0
• .NET Core 2.0 Web API

接口ISearchSettings >類SearchSettings
（基本上，這里的所有屬性，除了1個布爾值，我們都可以根據需要單身。一個布爾值有點告訴我們是使用內部搜索還是使用天藍色搜索）

應用啟動時，出現以下錯誤：

System.InvalidOperationException：配置無效。 創建類型為IOptionsSnapshot <SearchSettings>的實例失敗。 類型為IOptionsSnapshot <SearchSettings>的注冊委托引發了異常。 無法從ASP.NET Core請求服務請求服務'IOptionsSnapshot <SearchSettings>。 請確保在活動HTTP請求的上下文中調用此方法。

在“配置服務”中：

services.AddOptions();  
services.Configure<ISearchSettings>(
    this.Configuration.GetSection("AzureSearchSettings"));  
services.Configure<SearchSettings>(
    this.Configuration.GetSection("AzureSearchSettings"));  
// The next line was added trying some other suggestions from similar
// errors. It didn't resolve the issue  
services.AddScoped(
    cfg => cfg.GetService<IOptionsSnapshot<SearchSettings>>().Value);  
...  
services.AddMvc();  
...  
IntegrateSimpleInjector();  

在IntegrateSimpleInjector中：

this.container.Options.DefaultScopedLifestyle =
    new AsyncScopedLifestyle();

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddSingleton<IControllerActivator>(
    new SimpleInjectorControllerActivator(this.container));
services.AddSingleton<IViewComponentActivator>(
    new SimpleInjectorViewComponentActivator(this.container));

services.EnableSimpleInjectorCrossWiring(this.container);
services.UseSimpleInjectorAspNetRequestScoping(this.container);

在InitializeContainer中：

// I have tried both Lifestyle Transient and Scoped
this.container.Register<IOptionsSnapshot<SearchSettings>>(
    () => app.GetRequestService<IOptionsSnapshot<SearchSettings>>(),
    Lifestyle.Transient);
...
this.container.AutoCrossWireAspNetComponents(app);

堆棧跟蹤：

at SimpleInjector.SimpleInjectorAspNetCoreIntegrationExtensions.GetRequestServiceProvider(IApplicationBuilder builder, Type serviceType)
at SimpleInjector.SimpleInjectorAspNetCoreIntegrationExtensions.GetRequestService[T](IApplicationBuilder builder)
at QuotingService.Startup.<>c__DisplayClass9_0.<InitializeContainer>b__0() in E:\Repos\QuotingService\QuotingService\Startup.cs:line 299
at lambda_method(Closure )
at SimpleInjector.InstanceProducer.BuildAndReplaceInstanceCreatorAndCreateFirstInstance()
at SimpleInjector.InstanceProducer.GetInstance()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.GetInstance()
at SimpleInjector.InstanceProducer.VerifyInstanceCreation()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.VerifyInstanceCreation()
at SimpleInjector.Container.VerifyInstanceCreation(InstanceProducer[] producersToVerify)
at SimpleInjector.Container.VerifyInternal(Boolean suppressLifestyleMismatchVerification)
at SimpleInjector.Container.Verify()
at QuotingService.Startup.Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime appLifetime) in E:\Repos\QuotingService\QuotingService\Startup.cs:line 229
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.Configure(IApplicationBuilder app)
at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()

關於什么需要更改才能使此工作有任何想法？
感謝您提供的出色產品以及所提供的任何幫助。

Answer 1

您應該避免在簡單的Injector注冊的委托中調用GetRequestService ，因為這種調用要求存在一個活動的HTTP請求，該請求在應用程序啟動期間將不可用。

而是依靠AutoCrossWireAspNetComponents從ASP.NET Core獲取IOptionsSnapshot<SearchSettings> 。

但是，要使其正常工作，您需要調用services.Configure<SearchSettings> 。

這是一個有效的配置：

public class Startup
{
    private Container container = new Container();

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json");
        this.Configuration = builder.Build();
    }

    public IConfigurationRoot Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        // ASP.NET default stuff here
        services.AddMvc();

        this.IntegrateSimpleInjector(services);

        services.Configure<SearchSettings>(
            Configuration.GetSection("SearchSettings"));
    }

    private void IntegrateSimpleInjector(IServiceCollection services)
    {
        container.Options.DefaultScopedLifestyle = new AsyncScopedLifestyle();

        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

        services.AddSingleton<IControllerActivator>(
            new SimpleInjectorControllerActivator(container));

        services.EnableSimpleInjectorCrossWiring(container);
        services.UseSimpleInjectorAspNetRequestScoping(container);
    }

    public void Configure(IApplicationBuilder app)
    {
        container.AutoCrossWireAspNetComponents(app);
        container.RegisterMvcControllers(app);

        container.Verify();

        // ASP.NET default stuff here
        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
}

使用此配置，您可以在所有位置注入IOptionsSnapshot<T> 。 例如在您的HomeController內部：

public class HomeController : Controller
{
    private readonly IOptionsSnapshot<SearchSettings> snapshot;

    public HomeController(
        IOptionsSnapshot<SearchSettings> snapshot)
    {
        this.snapshot = snapshot;
    }
}