在MVC 5應用程序中使用autofac注入SignalR Hub的依賴關係

Question

我想將SignalR 2帶入一個現有項目，在該項目中使用autofac執行所有依賴項注入，並且在Global.asax中執行所有依賴項配置。我發現Autofac.SignalR包使用SignalR和autofac及其accompanying documentation。

我遵循提供的文檔中的示例，並遵循使用RegisterHubs函數的建議，而不是定義我的各個集線器依賴項。

不幸的是我的HUB類試圖從lifetimeScope

Autofac.Core.DependencyResolutionException was unhandled by user code 
HResult=-2146233088 
Message=No scope with a Tag matching 'AutofacWebRequest' is 
visible from the scope in which instance was requested. 
This generally indicates that a component registered as per-HTTP 
request is being requested by a SingleInstance() component 
(or a similar scenario.) Under the web integration always request 
dependencies from the DependencyResolver.Current or 
ILifetimeScopeProvider.RequestLifetime, never from the container itself. 

我一直沒能得到DependencyResolver.Current或ILifeTimeScopeProvider爲我工作解決的依賴時，得到以下運行時錯誤。

我的依賴性的配置是如下

var builder = new ContainerBuilder(); 
    .RegisterControllers(typeof (MvcApplication).Assembly); 
    .RegisterHubs(Assembly.GetExecutingAssembly()); 
    ... 
var container = builder.Build(); 

// Set dependency resolver for MVC 
DependencyResolver.SetResolver(new AutofacDependencyResolver(container)); 

// Set dependency resolver for Web API 
GlobalConfiguration.Configuration.DependencyResolver = new AutofacWebApiDependencyResolver(container); 

// Set the dependency resolver for SignalR 
DependencyResolver.SetResolver(new AutofacDependencyResolver(container)); 

var signalRDependencyResolver = new Autofac.Integration.SignalR.AutofacDependencyResolver(container); 
GlobalHost.DependencyResolver = signalRDependencyResolver; 

我還設置了根據該示例我的轂類：

public class BaseHub : Hub 
{ 
    protected readonly ILifetimeScope _hubLifetimeScope; 
    private static IUserSignalRConnectionRepository _userSignalRConnectionRepository; 

    public BaseHub(ILifetimeScope lifetimeScope) : base() 
    { 
     _hubLifetimeScope = lifetimeScope.BeginLifetimeScope(); 

     _userSignalRConnectionRepository = _hubLifetimeScope.Resolve<IUserSignalRConnectionRepository>(); 
    } 

    protected override void Dispose(bool disposing) 
    { 
     // Dipose the hub lifetime scope when the hub is disposed. 
     if (disposing && _hubLifetimeScope != null) 
      _hubLifetimeScope.Dispose(); 

     base.Dispose(disposing); 
    } 
} 

在幼獸類發生在線路的異常

_userSignalRConnectionRepository = _hubLifetimeScope.Resolve<IUserSignalRConnectionRepository>(); 

Answer 1

您應該在註冊您的IUserSignalRConnectionRepository的位置包含代碼。

錯誤消息似乎表明此相關性使用InstancePerHttpRequest()進行了註冊，這相當於InstancePerMatchingLifetimeScope("AutofacWebRequest")。這個範圍是爲MVC請求自動創建的，但不適用於SignalR請求（這可能是一件好事，因爲它們可以無限期地持續）。

您可以通過致電lifetimeScope.BeginLifetimeScope("AutofacWebRequest");解決此問題。而不是在您的Hub構造函數中使用lifetimeScope.BeginLifetimeScope();。

或者，您可以使用InstancePerDependency()（這是默認值）或SingleInstance()而不是InstancePerHttpRequest()來註冊IUserSignalRConnectionRepository。