Question

最近使用SimpleInjector的AutoFac新手，但由于我已升级到vNext / .NET5，因此AutoFac似乎已更新以使用它，因此请改用AutoFac。

我想要做的就是确保在每个请求上创建我的DbContext。我可以使用.InstancePerRequest()来做到这一点，但当我这样做时（我已添加到我的所有代码中），我似乎收到了错误消息

Autofac.Core.DependencyResolutionException没有带标记的范围匹配＆＃39; AutofacWebRequest＆＃39;从范围可见请求实例。这通常表示一个组件 a请求注册为每个HTTP请求 SingleInstance（）组件（或类似场景。）在Web下集成始终请求来自的依赖项 DependencyResolver.Current或ILifetimeScopeProvider.RequestLifetime，从来没有从容器本身。

我相信这是说根据HTTP请求没有请求某些内容，所以什么都不会？是对的吗？如果是这样，有点似乎有点愚蠢。我不在乎我的服务和验证器只创建一次，但我需要在每个请求上创建DbContext，因为当多个请求连接到我的WebApi时，我不断收到错误

第二个操作在此前一个上下文之前开始异步操作完成。

但是，如果我自己一个接一个地执行这些调用，那么它们都可以正常工作。

我使用的是EntityFramework 6.1，而不是EF7，因为EF7还远未完成。

我有自己的AutoFac模块，就像这样

public class SetupModule : Autofac.Module
{
    protected override void Load(ContainerBuilder builder)
    {
        // IDataContext
        builder.Register((c) =>
            {
                var appEnv = c.Resolve<IApplicationEnvironment>();
                var configBuilder = new ConfigurationBuilder(appEnv.ApplicationBasePath)
                    .AddJsonFile("config.json");
                var configuration = configBuilder.Build();

                return new DataContext(configuration["Data:MyConnection:ConnectionString"]);
            })
            .As<IDataContext>()
            .InstancePerRequest();

        // Validators
        builder.RegisterAssemblyTypes(System.Reflection.Assembly.GetAssembly(typeof(IValidator)))
            .Where(t => typeof(IValidator).IsAssignableFrom(t))
            .AsImplementedInterfaces()
            .InstancePerRequest();

        // Services
        builder.RegisterType<ContentService>().As<IContentService>().InstancePerRequest();

    }
}

我的DataContext就像一个带有构造函数的标准DbContext类，只需要使用connectionString

public DataContext : IDataContext {
    public DataContext(string connectionString)
        : base(connectionString)
        {

        }
}

在我的Startup.cs文件中，我使用此

注册

public IServiceProvider ConfigureServices(IServiceCollection services)
{
    // Create the Autofac container builder.
    var builder = new ContainerBuilder();
    builder.RegisterModule(new AutoFac.SetupModule());
    builder.Populate(services);

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

    // Resolve and return the service provider.
    return container.Resolve<IServiceProvider>();
}

有人能告诉我到底我错过了什么吗？是否与我如何创建DataContext有关，因为需要这样做才能从config.json文件中获取connectionString。

提前致谢

注意：如果我更改为.InstancePerDependency()我的错误会停止，但我不认为这是我想要的所有对象

UPDATE 这是stacktrace

at Autofac.Core.Lifetime.MatchingScopeLifetime.FindScope(ISharingLifetimeScope mostNestedVisibleScope) 
at Autofac.Core.Resolving.InstanceLookup..ctor(IComponentRegistration registration, IResolveOperation context, ISharingLifetimeScope mostNestedVisibleScope, IEnumerable<Parameter> parameters)
at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable<Parameter> parameters)
at Autofac.Core.Resolving.ResolveOperation.ResolveComponent(IComponentRegistration registration, IEnumerable<Parameter> parameters) 
at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable<Parameter> parameters) 
at Autofac.Core.Lifetime.LifetimeScope.ResolveComponent(IComponentRegistration registration, IEnumerable<Parameter> parameters) 
at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable<Parameter> parameters, Object& instance) 
at Autofac.ResolutionExtensions.ResolveOptionalService(IComponentContext context, Service service, IEnumerable<Parameter> parameters) 
at Autofac.ResolutionExtensions.ResolveOptional(IComponentContext context, Type serviceType, IEnumerable<Parameter> parameters) 
at Autofac.ResolutionExtensions.ResolveOptional(IComponentContext context, Type serviceType) 
at Autofac.Framework.DependencyInjection.AutofacServiceProvider.GetService(Type serviceType) 
at Microsoft.Framework.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired) 
.lambda_method(Closure , IServiceProvider , Object[] ) 
at Microsoft.AspNet.Mvc.DefaultTypeActivatorCache.CreateInstance<TInstance>(IServiceProvider serviceProvider, Type implementationType) 
at Microsoft.AspNet.Mvc.DefaultControllerActivator.Create(ActionContext actionContext, Type controllerType) 
at Microsoft.AspNet.Mvc.DefaultControllerFactory.CreateController(ActionContext actionContext) 
at Microsoft.AspNet.Mvc.Core.ControllerActionInvoker.CreateInstance() 
at Microsoft.AspNet.Mvc.Core.FilterActionInvoker.<InvokeAllActionFiltersAsync>d__49.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Mvc.Core.FilterActionInvoker.<InvokeExceptionFilterAsync>d__48.MoveNext() 
--- exception rethrown --- 
at Microsoft.AspNet.Mvc.Core.FilterActionInvoker.<InvokeAsync>d__41.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Mvc.MvcRouteHandler.<InvokeActionAsync>d__7.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Mvc.MvcRouteHandler.<RouteAsync>d__6.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Mvc.Routing.InnerAttributeRoute.<RouteAsync>d__10.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Routing.RouteCollection.<RouteAsync>d__9.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Builder.RouterMiddleware.<Invoke>d__4.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Hosting.Internal.RequestServicesContainerMiddleware.<Invoke>d__3.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Hosting.Internal.HostingEngine.<>c__DisplayClass29_0.<<Start>b__0>d.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Loader.IIS.RuntimeHttpApplication.<ProcessRequestAsyncImpl>d__13.MoveNext() 
--- exception rethrown --- 
at Microsoft.AspNet.Loader.IIS.RuntimeHttpApplication.<ProcessRequestAsyncImpl>d__13.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Loader.IIS.HttpApplicationBase.<InvokeProcessRequestAsyncImpl>d__9.MoveNext()

Answer 1

似乎发生了两件事中的一件或两件：

Autofac未与ASP.NET正确集成，并且尚未启动标记为AutofacWebRequest的新生命周期范围。
您正在解析在其祖先未包含标记为InstancePerRequest()的生命周期范围的生命周期范围内已注册为AutofacWebRequest的组件。

查看堆栈跟踪，似乎第一种情况比第二种情况更可能，因为在构造控制器时发生了异常。

Answer 2

简短的回答是，你不能有更长的生命取决于短暂的生命

示例：每个请求的实例依赖单个实例是错误的

所以典型的默认值是每个依赖项的实例（瞬态，因此每次需要一个实例时，都会创建一个新实例）。

如果每个请求都有实例A B是单例

然后A取决于B，没问题但是如果B依赖于A，则会遇到问题，因为B永远不会被重新创建，而取决于A将要在每个范围内重新创建。

其他库有时会让您犯此错误并独自发现（非常痛苦）

似乎AutoFact在让您知道作用域层次结构有问题的方面做得更好。

没有标记匹配的范围＆＃39; AutofacWebRequest＆＃39;从范围可见

2 个答案: