带ASP.Net Core 2.0 IOptions的简单注入器快照注入

Question

I was trying what was suggested in bug #429 and am getting the same error he reported there but then never provided the stack trace for. I have also read, and have used until recently, your guidance on not using IOptions and related classes. We are at a point where the IOptionsSnapshot is really needed as we are running stuff in Azure and need to be able to flip options on/off on the fly as we hit limits and restarting the service is not an option as it takes upwards of 5 minutes to start initially due to some third party pieces we require.

This is what we have setup:

• Simple Injector 4.3.0
• .NET Core 2.0 Web API

interface ISearchSettings -> class SearchSettings
(basically all of the properties in here except for 1 boolean we can singleton if needed. The one boolean is a bit telling us whether to use inhouse or azure searching)

When the app is starting, I receive the following error:

System.InvalidOperationException: The configuration is invalid. Creating the instance for type IOptionsSnapshot<SearchSettings> failed. The registered delegate for type IOptionsSnapshot<SearchSettings> threw an exception. Unable to request service 'IOptionsSnapshot<SearchSettings> from ASP.NET Core request services. Please make sure this method is called within the context of an active HTTP request.

In Configure Services:

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();  

In IntegrateSimpleInjector:

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);

In InitializeContainer:

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

Stacktrace:

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()

Any ideas on what needs to be changed to get this working?
Thanks for the awesome product and any help provided.

Answer 1

You should prevent making calls to GetRequestService inside a Simple Injector-registered delegate, since this such call requires the existence of an active HTTP request, which will not be available during application startup.

Instead, rely upon AutoCrossWireAspNetComponents to get IOptionsSnapshot<SearchSettings> from ASP.NET Core.

For this to work, however, you need to have called services.Configure<SearchSettings> .

Here is a working configuration:

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?}");
        });
    }
}

With this config, you can inject IOptionsSnapshot<T> everywhere. For instance inside your HomeController :

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

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