Autofac DbContext 已被释放

Question

我已经阅读了这篇文章DbContext has been disposed and autofac，但我仍然遇到同样的错误：

操作无法完成，因为 DbContext 已被释放。

public class EFRepository : IRepository
{
    private EFDbContext context;

    public EFRepository(EFDbContext ctx)
    {
        context = ctx;
    }

    public TEntity FirstOrDefault<TEntity>(Expression<Func<TEntity, bool>> predicate, params Expression<Func<TEntity, object>>[] includes)
        where TEntity : class, IContextEntity
    {
        IQueryable<TEntity> query = includes.Aggregate<Expression<Func<TEntity, object>>, IQueryable<TEntity>>
                     (context.Set<TEntity>(), (current, expression) => current.Include(expression));            

        return query.FirstOrDefault(predicate);
    }
}

在 Global.asax 中

ContainerBuilder builder = new ContainerBuilder();
builder.RegisterControllers(typeof(MvcApplication).Assembly);

builder.Register<IRepository>(c => new EFRepository(new EFDbContext()));

ILifetimeScope container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

控制器注入：

public class AccountController : Controller
{
    private readonly IRepository repository;
    private readonly IMembershipService membershipService;        

    public AccountController(IRepository repo, IMembershipService mmbrSvc)
    {
        repository = repo;
        membershipService = mmbrSvc;
    }
    [HttpPost]        
    public ActionResult Login(LoginViewModel viewModel)
    {
        if (!ModelState.IsValid)             
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);            

        string returnUrl = (string)TempData["ReturnUrl"];
        LoginDto accountDto = viewModel.GetLoginStatus(repository, membershipService, returnUrl);
        string accountDtoJson = JsonHelper.Serialize(accountDto);

        return Content(accountDtoJson, "application/json");
    }
}

然后在 LoginViewModel 中：

public LoginDto GetLoginStatus(IRepository repo, IMembershipService mmbrSvc, string returnUrl)
    {
        repository = repo;
        membershipService = mmbrSvc;

        User user = repository.FirstOrDefault<User>(x => x.Username == Username, x => x.Membership);
    ............
    ............
    }

Answer 1

您需要向 AutoFac 注册 DbContext 本身并为其提供适当的生命周期。 InstancePerDependency 通常适用于存储库。

builder.RegisterType<EFDbContext>().AsSelf().InstancePerDependency();

然后，你不需要给存储库注册一个对象，只需注册类型（记得指定生命周期）：

builder.Register<EFRepository>().As<IRepository>().InstancePerLifetimeScope();