为什么在HttpRequest结束之前autofac会处理对象？

Question

我正在编写一个ASP.NET MVC网站，使用autofac进行依赖项注入，并将Mindscape的Lightspeed用作ORM。有一个UserRepository类，该类取决于光速UnitOfWork，并为Logon控制器提供服务。

问题：在UserRepository使用完UnitOfWork之前，将其处置。

  public class UserRepository : IUserRepository
  {
    private readonly BluechipModelUnitOfWork _unitOfWork;

    public UserRepository(BluechipModelUnitOfWork unitOfWork)
    {
        _unitOfWork = unitOfWork;
    }
    public Principal GetPrincipal(string name)
    {
        // This line throws an ObjectDisposedException - UnitOfWork is already disposed.
        return _unitOfWork.Principals.FirstOrDefault(p => p.Name == name);
    }
    ...

在Global.asax中，依存关系接线如下：

public class MvcApplication : HttpApplication, IContainerProviderAccessor
{
    private static void RegisterAutofac()
    {
        var builder = new ContainerBuilder();

        // Register the lightspeed context as a singleton
        builder.RegisterInstance(new LightSpeedContext<BluechipModelUnitOfWork>("LightSpeedBluechip"))
            .As<LightSpeedContext<BluechipModelUnitOfWork>>()
            .SingleInstance();

        // Register the unit of work constructor so that a new instance is bound to each HttpRequest
        builder.Register(c => c.Resolve<LightSpeedContext<BluechipModelUnitOfWork>>().CreateUnitOfWork())
            .As<BluechipModelUnitOfWork>()
            .InstancePerLifetimeScope();

        // Register user repository to be one instance per HttpRequest lifetime
        builder.Register(c => new UserRepository(c.Resolve<BluechipModelUnitOfWork>()))
            .As<IUserRepository>()
            .InstancePerLifetimeScope();

        builder.Register(c => new CurrentUserService(
                                  c.Resolve<HttpSessionState>(),
                                  c.Resolve<IUserRepository>(),
                                  c.Resolve<IMembershipService>())
            ).As<ICurrentUserService>()
            .CacheInSession();

        builder.RegisterType<ExtensibleActionInvoker>().As<IActionInvoker>();
        builder.RegisterControllers(Assembly.GetExecutingAssembly()).PropertiesAutowired().InjectActionInvoker();
        builder.RegisterModelBinders(Assembly.GetExecutingAssembly());

        // Set the container provider up with registrations.    
        _containerProvider = new ContainerProvider(builder.Build());

        // Set the controller factory using the container provider.    
        ControllerBuilder.Current.SetControllerFactory(new AutofacControllerFactory(_containerProvider));

鉴于上述注册，为什么autofac会处理UnitOfWork（

Answer 1

我能够找到问题所在-这是一个愚蠢但微妙的陷阱...我注册了CurrentUserService类，如下所示：

    builder.Register(c => new CurrentUserService(
                                  c.Resolve<HttpSessionState>(),
                                  c.Resolve<IUserRepository>(),
                                  c.Resolve<IMembershipService>())
            ).As<ICurrentUserService>()
            .CacheInSession();

问题出在CacheInSession（）上，因为CurrentUserService依赖于IUserRepository，它是autofac忠实地注入的，但是在第一个请求结束时进行了处理。

这揭示了一些显而易见的东西，但是在连接依赖项注入时需要注意：

确保高阶从属始终与它们所依赖的服务具有相同或较短的生存期。就我而言，解决方案是更改以上代码：

        builder.Register(c => new CurrentUserService(
                                  c.Resolve<HttpSessionState>(),
                                  c.Resolve<IUserRepository>(),
                                  c.Resolve<IMembershipService>())
            ).As<ICurrentUserService>()
            .InstancePerLifetimeScope();

....这样可以防止CurrentUserService脱离其依赖的实例。