SignalR - How to access user mapping in other server side class to send notifications to a particular userRSS

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  Hyder Ahmed

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  SignalR - How to access user mapping in other server side class to send notifications to a partic...

  Jun 10, 2017 01:00 PM|Hyder Ahmed|LINK

  I have implemented In-memory storage mapping in my MVC project to store the userId and its related connectionsId as shown in the mapping link below. The problem is that I am not able to access the mapping instance in the other server side class and send notification to a particular user who are connected. How should I modify Hub or SendNotification class to send Notification.

  // here is the sample hub class with onconnected and disconnected same as in mapping link
  public class NotificationHub : Hub
  {
      private readonly static ConnectionMapping<string> _connections =  new ConnectionMapping<string>();
  
      public void SendChatMessage(string who, string message)
      {
          string name = Context.User.Identity.Name;
  
          foreach (var connectionId in _connections.GetConnections(who))
          {
              Clients.Client(connectionId).addChatMessage(name + ": " + message);
          }
      }
  }
  
  // other server class where to call hub
  public class SendNotification
  {
      Public void SaveToDb(string userName, class entity)
      {
          // save to database call
          // send Notification to User userName through SignalR if user Exists in Mapping
      }
  }

  Here's a SignalR Mapping link which I have implemented (https://docs.microsoft.com/en-us/aspnet/signalr/overview/guide-to-the-api/mapping-users-to-connections)!

  Here's How to access hub outside (https://docs.microsoft.com/en-us/aspnet/signalr/overview/guide-to-the-api/hubs-api-guide-server#callfromoutsidehub)!

• • Reply
  JBetancourt

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  Re: SignalR - How to access user mapping in other server side class to send notifications to a pa...

  Jun 10, 2017 11:59 PM|JBetancourt|LINK

  var context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
  foreach (var connectionId in _connections.GetConnections(userName))
  {
  	context.Clients.Client(connectionId).addChatMessage(name + ": " + message);
  }
  

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  EvenMa

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  286 Posts

  Re: SignalR - How to access user mapping in other server side class to send notifications to a pa...

  Jun 12, 2017 12:26 PM|EvenMa|LINK

  Hi Hyder Ahmed,

  According to your description, you could use GlobalHost.ConnectionManager.GetHubContext<NotificationHub>(), see the following code:

  (1) NotificationHub.cs

  [HubName("NotificationHub")]
  public class NotificationHub : Hub
  {
       private readonly static ConnectionMapping<string> _connections = new ConnectionMapping<string>();
       public static void SendNotification(string who, string message)
       {
           IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
           foreach (var connectionId in _connections.GetConnections(who))
           {
               //get client from hubcontext by connectionId
               var client = context.Clients.Client(connectionId);
               if (client != null)
               {
                    //notify client
                    client.addChatMessage(who + ":" + message);
               }
            }
       }
  }

  (2) SendNotification example:

  public class SendNotification
  {
       public void SaveToDb(string userName)
       {
            // save to database call
            // send Notification to User userName through SignalR if user Exists in Mapping
            NotificationHub.SendNotification("username", "Save To Db succeeds");
       }
  }

   

  If you have any other questions, please feel free to contact me any time.

  Best Regards

  Even