Question

我在asp net core web api中使用了asp net core 2.0 和新的SignalR 1.0.0-alpha1-final 。

我正在将SignalR hub（LiveDataHandler）注入我的控制器（DataController）

public DataController(IOptions<TheAppSettings> config, ILogger<DataController> logger, LiveDataHandler liveDataHandler)
{
    // need to use data repository
    this.dataRepository = new DataRepository(config.Value.db);
}

并配置到我的SignalR Hub

public LiveDataHandler(IOptions<TheAppSettings> config)
{
    // need to use data repository
    this.dataRepository = new DataRepository(config.Value.db);
}

设置signalR并设置我

public void ConfigureServices(IServiceCollection services)
{
    // app settings to inject
    var theAppSettings = Configuration.GetSection("TheAppSettings");
    services.Configure<TheAppSettings>(theAppSettings);

    // Use WebSockets
    services.AddSignalR();

    ...
}

和

public void Configure(IApplicationBuilder app, IServiceProvider serviceProvider)
{
     app.UseSignalR(routes =>
     {
         routes.MapHub<LiveDataHandler>("livedata");
     });

     ....
}

这个编译没有任何问题，SignalR连接完全正常，但是当我向我的控制器发出api调用时，我会收到一个错误（抱歉整个跟踪......）

System.InvalidOperationException: Unable to resolve service for type 'LoadingScreen.API.Hubs.LiveDataHandler' while attempting to activate 'LoadingScreen.API.Controllers.DataController'.
   at Microsoft.Extensions.Internal.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
   at lambda_method(Closure , IServiceProvider , Object[] )
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass4_0.<CreateActivator>b__0(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass5_0.<CreateControllerFactory>g__CreateController0(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeInnerFilterAsync>d__14.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeNextResourceFilter>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeFilterPipelineAsync>d__17.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeAsync>d__15.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware.<Invoke>d__7.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.<Invoke>d__6.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Hosting.Internal.RequestServicesContainerMiddleware.<Invoke>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Frame`1.<ProcessRequestsAsync>d__2.MoveNext()

现在从错误中我可以粗略地推断出在实例化时将SignalR集线器注入控制器存在问题，但我不确定如何解决这个问题。任何想法如何得到这个？

在使用SignalR之前，我使用的是WebSosketManager库，它使用LiveDataHandler作为服务，注入工作没有问题：

app.UseWebSockets();
app.MapWebSocketManager("/liveData", serviceProvider.GetService<LiveDataHandler>());

所以我只假设，signalR会以类似的方式工作......

Answer 1

基于提供的代码，您似乎忘记了注册IOptions<T>解析所需的依赖项：

public void ConfigureServices(IServiceCollection services)
{
   // Adds services required for using options.
    services.AddOptions();

    // app settings to inject
    var theAppSettings = Configuration.GetSection("TheAppSettings");
    services.Configure<TheAppSettings>(theAppSettings);

    ...
 }

使用net core error将SignalR Hub注入Controller

1 个答案: