autofac with signalr no parameterless constructor defined for this object

Question

我在当前的 Asp 项目中使用 autofac，一切正常，直到我决定在 signalR Hub 中使用依赖注入

这是我的创业公司 class

public partial class Startup
{
    public void Configuration(IAppBuilder app)
    {
        ConfigureAuth(app);
        var builder = new ContainerBuilder();
        builder.RegisterControllers(Assembly.GetExecutingAssembly());
        builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerLifetimeScope();
        builder.RegisterType<DbFactory>().As<IDbFactory>().InstancePerLifetimeScope();
        //builder.RegisterHubs(Assembly.GetExecutingAssembly());
        builder.RegisterType<DiscussionHub>();
        // Repositories
        builder.RegisterAssemblyTypes(typeof(LanguagesRepository).Assembly)
            .Where(t => t.Name.EndsWith("Repository"))
            .AsImplementedInterfaces().InstancePerRequest();
        // Services
        builder.RegisterAssemblyTypes(typeof(LanguageService).Assembly)
           .Where(t => t.Name.EndsWith("Service"))
           .AsImplementedInterfaces().InstancePerRequest();

        IContainer container = builder.Build();
        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        var config = new HubConfiguration
        {
            Resolver = new Autofac.Integration.SignalR.AutofacDependencyResolver(container)
        };
        app.UseAutofacMiddleware(container);
        AutoMapperConfiguration.Configure();
        app.MapSignalR("/signalr",config);
    }
}

这是我的中心

public class DiscussionHub : Hub
{
    private readonly IDiscussionService _discussionService;
    public DiscussionHub(IDiscussionService discussionService)
    {
        _discussionService = discussionService;
    }}

错误是我的集线器上没有无参数构造函数？有什么建议吗？！

Answer 1

你应该注册你的 hub ExternallyOwned 它应该自己管理 lifetimescope。这意味着 autofac 不会处理它们。

其次，一切都将从您中心的根容器中解决。这意味着 Per Dependency 或 Per LifeTimeScope 将与您的中心一起使用（永远与应用程序一起使用）。所以你应该在你的中心管理生命周期。

即使我们管理您中心的生命周期，Per Request 也不会得到支持。因此，当我们创建新的 lifetimescope 时，我们将使用 AutofacWebRequest 标签创建它。这样，我们就可以解析您的 Per Request 实例。但请注意，此实例与正常请求生命周期范围内的其他实例完全不同。

你的 Hub 应该是这样的：

public class DiscussionHub  : Hub
{
  private readonly ILifetimeScope _hubLifetimeScope;
  private readonly IDiscussionService  _discussionService;

  public MyHub(ILifetimeScope lifetimeScope)
  {
    // Create a lifetime scope for the hub.
    _hubLifetimeScope = lifetimeScope.BeginLifetimeScope("AutofacWebRequest");

    // Resolve dependencies from the hub lifetime scope.
    _discussionService = _hubLifetimeScope.Resolve<IDiscussionService>();
  }

  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);
  }
}

你的登记表应该是这样的：

  .
  .
  builder.RegisterType<DiscussionHub>().ExternallyOwned();
  var container = builder.Build();
  GlobalHost.DependencyResolver = new   Autofac.Integration.SignalR.AutofacDependencyResolver(container);
  .
  .

Owin 集成：

public void Configuration(IAppBuilder app)
  {
    var builder = new ContainerBuilder();

    // STANDARD SIGNALR SETUP:

    // Get your HubConfiguration. In OWIN, you'll create one
    // rather than using GlobalHost.
    var config = new HubConfiguration();

    // Register your SignalR hubs.
    builder.RegisterHubs(Assembly.GetExecutingAssembly());

    // Set the dependency resolver to be Autofac.
    var container = builder.Build();
    config.Resolver = new AutofacDependencyResolver(container);

    // OWIN SIGNALR SETUP:

    // Register the Autofac middleware FIRST, then the standard SignalR middleware.
    app.UseAutofacMiddleware(container);
    app.MapSignalR("/signalr", config);
  }

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autofac with signalr no parameterless constructor defined for this object

autofac with signalr no parameterless constructor defined for this object

c#

asp.net

signalr

autofac

signalr-hub