C#学习教程：在Owin启动期间，SimpleInjector无法为每个WebAPI请求注册类注入分享

我正在使用Owin，Web API，entity framework，ASP.NET身份创建API。 我使用Simple Injector作为我选择的DI框架。

在Owin启动过程中，我想用一些示例数据为我的数据库建立种子。 这是由实现IDatabaseInitializer的类处理的，它看起来像这样：

 public class MyDbInitializer : DropCreateDatabaseAlways { private readonly IUserManager _userManager; public MyDbInitializer(IUserManager userManager) { _userManager = userManager; } protected override void Seed(MyDataContext context) { SeedIdentities(); } private void SeedIdentities() { var user = new User { UserName = "someUsername", Email = "some@email.com" }; _userManager.CreateAsync(user, "Password"); } 

IUserManager是ASP.NET Identiy UserManager类的代理，它间接依赖于IUnitOfWork 。 如果你想知道， IUserManager注册如下：

 container.Register(typeof(IUserManager), () => container.GetInstance().Create()); 

因为我想为每个Web API请求使用一个工作单元，所以我已将IUnitOfWork注册如下：

 container.RegisterWebApiRequest(); 

除了解析MyDbInitializer类中的IUserManager依赖项之外，这对于所有事情都很MyDbInitializer 。 在应用程序启动期间，SimpleInjector失败并出现以下ActivationException：

 SimpleInjector.ActivationException was unhandled by user code HResult=-2146233088 Message=The registered delegate for type IUserManagerFactory threw an exception. The IUnitOfWork is registered as 'Web API Request' lifestyle, but the instance is requested outside the context of a Web API Request. Source=SimpleInjector StackTrace: at SimpleInjector.InstanceProducer.GetInstance() at SimpleInjector.Container.GetInstance[TService]() at Project.WebApi.CompositionRoot.SimpleInjectorCompositionRoot.b__c() in c:codeProjectProject.WebApiCompositionRootSimpleInjectorCompositionRoot.cs:line 130 at lambda_method(Closure ) at lambda_method(Closure ) at SimpleInjector.InstanceProducer.GetInstance() InnerException: SimpleInjector.ActivationException HResult=-2146233088 Message=The IUnitOfWork is registered as 'Web API Request' lifestyle, but the instance is requested outside the context of a Web API Request. Source=SimpleInjector StackTrace: at SimpleInjector.Scope.GetScopelessInstance[TService,TImplementation](ScopedRegistration`2 registration) at SimpleInjector.Scope.GetInstance[TService,TImplementation](ScopedRegistration`2 registration, Scope scope) at SimpleInjector.Advanced.Internal.LazyScopedRegistration`2.GetInstance(Scope scope) at lambda_method(Closure ) at SimpleInjector.InstanceProducer.GetInstance() InnerException: 

我猜Owin Startup.cs类被认为是在Web API请求生命周期之外，并且数据库初始化程序中的构造函数注入失败，因为它由Startup.cs类调用。

我不确定如何解决这个问题。 我应该使用混合生活方式来注册IUnitOfWork ，还是有更好的解决方案？

 // using SimpleInjector.Extensions.ExecutionContextScoping; using (container.BeginExecutionContextScope()) { var initializer = container.GetInstance(); intializer.InitializeDatabase(); } 

 protected async override Task SendAsync( HttpRequestMessage request, CancellationToken cancellationToken) { // Trigger the creation of the DependencyScope to ensure the instance // is resolved within that scope. request.GetDependencyScope(); }