StartofConfig中的Autofac Web API 2和Owin解析

Question

我有一個既是OWIN又是Web API 2的項目。我盡力遵循說明。 在我的StartupConfig類的Configration方法中，我有這個：

// Get our configuration
var config = new HttpConfiguration();
var container = ConfigureInversionOfControl(app, config);
var scope = config.DependencyResolver.GetRequestLifetimeScope();
var serverOptions = ConfigureOAuthTokenGeneration(app, scope);

//** removed for brevity **//

// Cors must be first, or it will not work
app.UseCors(CorsOptions.AllowAll);

// Register the Autofac middleware FIRST. This also adds
// Autofac-injected middleware registered with the container.
app.UseAutofacMiddleware(container);
//app.UseAutofacWebApi(config);
app.UseOAuthAuthorizationServer(serverOptions);
app.UseWebApi(config);

我的ConfigurInversionOfControl方法如下所示：

private static IContainer ConfigureInversionOfControl(IAppBuilder app, HttpConfiguration config)
{

    // Create our container
    var builder = new ContainerBuilder();

    // You can register controllers all at once using assembly scanning...
    builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

    // Add our dependencies (Can't use life because this is available to all controllers http://stackoverflow.com/questions/36173210/get-same-instance-of-a-component-registered-with-autofac-as-instanceperlifetimes)
    builder.RegisterType<UnitOfWork<DatabaseContext>>().As<IUnitOfWork>().InstancePerRequest();

    // Register our services
    builder.Register(c => new AdvancedEncryptionStandardProvider(ConfigurationManager.AppSettings["rm:key"], ConfigurationManager.AppSettings["rm:secret"])).As<IAdvancedEncryptionStandardProvider>();
    builder.RegisterType<LogService>().As<ILogService>();
    builder.RegisterType<EmailService>().As<IEmailService>();
    builder.RegisterType<RefreshTokenService>().As<IRefreshTokenService>();

    // Register our providers
    builder.Register(c => new SendGridProvider(c.Resolve<IUnitOfWork>(), c.Resolve<IEmailService>(), ConfigurationManager.AppSettings["SendGridApiKey"])).As<ISendGridProvider>();
    builder.RegisterType<LogProvider>().As<ILogProvider>();
    builder.RegisterType<RefreshTokenProvider>().As<IAuthenticationTokenProvider>();
    builder.RegisterType<OAuthProvider>().As<OAuthProvider>();

    // Build
    var container = builder.Build();

    // Lets Web API know it should locate services using the AutofacWebApiDependencyResolver
    config.DependencyResolver = new AutofacWebApiDependencyResolver(container);

    // Return our container
    return container;
}

現在我已經設置好了（我假設正確）。 如何解決StartupConfig類中的某個服務？ 我需要能夠創建OAuthProvider和RefreshTokenProvider的實例。 我嘗試過類似的東西：

// Get our providers
var authProvider = scope.Resolve<OAuthProvider>();
var refreshTokenProvider = scope.Resolve<IAuthenticationTokenProvider>();

// Create our OAuth options
return new OAuthAuthorizationServerOptions()
{
    AllowInsecureHttp = true, // TODO: Remove this line
    TokenEndpointPath = new PathString("/oauth/access_token"),
    AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
    AccessTokenFormat = new Business.Authentication.JwtFormat("http://localhost:62668"),
    Provider = authProvider,
    RefreshTokenProvider = refreshTokenProvider
};

但當它到達行var authProvider = scope.Resolve<OAuthProvider>(); ，我得到一個錯誤說明：

參數不能為null：參數名稱：context

現在我假設還沒有創建上下文，所以我認為我的決心做錯了。 有人可以幫忙嗎？

Answer 1

這其實很簡單。 我需要更改范圍：

var scope = config.DependencyResolver.GetRequestLifetimeScope();

至

var scope = config.DependencyResolver.GetRootLifetimeScope();

我假設因為StartupConfig類中沒有“請求”。 無論如何，改變這個解決了我的問題。