如何通过SignalR将消息发送给特定用户（身份标识）？

问题描述：

在我Startup.Auth.cs：如何通过SignalR将消息发送给特定用户（身份标识）？

private static void ConfigSignalR(IAppBuilder appBuilder) 
{ 
    appBuilder.MapSignalR(); 
    var idProvider = new PrincipalUserIdProvider(); 
    GlobalHost.DependencyResolver.Register(typeof(IUserIdProvider),() => idProvider); 
}

我UserHub.cs：

public class UserHub : Hub 
{ 
}

在服务器端，在我的API控制器动作之一（与网格更新认沽）：

[...] 
var userHub = GlobalHost.ConnectionManager.GetHubContext<UserHub>(); 
// Line below does not work 
// userHub.Clients.User(userId).send("Hi"); 

// But this line below works when sending the message to everybody 
userHub.Clients.All.send("Hi"); 

return Request.CreateResponse(HttpStatusCode.OK);

在JS View客户端：

@Request.IsAuthenticated 
{ 
    <script> 

     $(function() { 
      var userHub = $.connection.userHub; 

      console.log(userHub.client); 

      userHub.client.send = function(message) { 
       alert('received: ' + message); 
      }; 

      $.connection.hub.start().done(function() { 
      }); 
     }); 
    </script> 
}

为什么在通过userId时我的客户端收不到任何东西？（也尝试通过userName，结果相同）。

[编辑] 技术上实现了正确的方法是充分利用IUserIdProvider执行：

https://docs.microsoft.com/en-us/aspnet/signalr/overview/guide-to-the-api/mapping-users-to-connections#IUserIdProvider
SignalR - Sending a message to a specific user using (IUserIdProvider) *NEW 2.0.0*

然而，我注意到，在我如果传递给GetUserId方法的IRequest对象的User属性始终设置为null ...

我的理解是最简单，最干净的方式做到这一点是将客户端和连接存储在OnConnected方法内的字典中。用户基于随机生成的连接ID，因此您传递的任何内容都不会匹配。 – willthiswork89

答

的解决方案实际上已经给出了另外一个问题，就在这里：https://stackoverflow.com/a/22028296/4636721

的问题是所有关于在Startup.Auth.cs初始化顺序： SignalR必须饼干后进行初始化和OwinContext初始化，如IUserIdProvider传递给GlobalHost.DependencyResolver.Register接收包含IRequest一个非空User其GetUserId方法：

public partial class Startup 
{ 
    public void ConfigureAuth(IAppBuilder appBuilder) 
    { 
     // Order matters here... 
     // Otherwise SignalR won't get Identity User information passed to Id Provider... 
     ConfigOwinContext(appBuilder); 
     ConfigCookies(appBuilder); 
     ConfigSignalR(appBuilder); 
    } 

    private static void ConfigOwinContext(IAppBuilder appBuilder) 
    { 
     appBuilder.CreatePerOwinContext(ApplicationDbContext.Create); 
     appBuilder.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create); 
     appBuilder.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create); 
     appBuilder.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create); 
     appBuilder.CreatePerOwinContext(LdapAdEmailAuthenticator.Create); 
    } 

    private static void ConfigCookies(IAppBuilder appBuilder) 
    { 
     appBuilder.UseCookieAuthentication(new CookieAuthenticationOptions 
     { 
      AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie, 
      LoginPath = new PathString("/Account/Login"), 
      Provider = new CookieAuthenticationProvider 
      { 
       OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, ApplicationUser> 
       (
        TimeSpan.FromHours(4), 
        (manager, user) => user.GenerateUserIdentityAsync(manager) 
       ) 
      } 
     }); 
     appBuilder.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie); 
     appBuilder.UseTwoFactorSignInCookie(DefaultAuthenticationTypes.TwoFactorCookie, TimeSpan.FromMinutes(5)); 
     appBuilder.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie); 
    } 

    private static void ConfigSignalR(IAppBuilder appBuilder) 
    { 
     appBuilder.MapSignalR(); 
     var idProvider = new HubIdentityUserIdProvider(); 
     GlobalHost.DependencyResolver.Register(typeof(IUserIdProvider),() => idProvider); 
    } 
}

使用IUserIdProvider下面，我明确宣布，我要使用的用户ID，而不是用户名由IUserIdProvider的缺省实现给定，又名PrincipalUserIdProvider：

public class HubIdentityUserIdProvider : IUserIdProvider 
{ 
    public string GetUserId(IRequest request) 
    { 
     return request == null 
      ? throw new ArgumentNullException(nameof(request)) 
      : request.User?.Identity?.GetUserId(); 
    } 
}

如何通过SignalR将消息发送给特定用户（身份标识）？

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