User Specific Notifications Using ASP.NET MVC And SignalR

Send specific user Notification using SignalR

In this section, we will work with a view to send notifications to specific users.

Index. cshtml

<div class="col-md-12">
    <h2>Say Hello</h2>
    <div id="messages"></div>
    <hr />
    <div class="form-group">
        <label for="email">User Email:</label>
        <input type="email" class="form-control" id="toUser" value="" placeholder="[email protected]"/>
    </div>
    <div class="form-group">
        <label for="pwd">Message:</label>
        <input type="password" class="form-control" id="myMessage" value="" placeholder="message"/>
    </div>

    <button type="submit" class="btn btn-default" id="submit">Submit</button>
</div>

Javascript

<script type="text/javascript">
    $("#submit").click(function (e) {
        e.preventDefault();
        var message = $("#myMessage").val();
        var sendtouser = $("#toUser").val();
        var Notification = { UserID: sendtouser, Message: message };
        $.ajax({
            type: "POST",
            url: "/api/Values/SendNotification",
            data: JSON.stringify(Notification),
            contentType: 'application/json; charset=utf-8',
            success: function (data) {
                //reset field
                $("#myMessage").val("");
            },
            error: function () {
                alert("Error occurred!!");
            }
        });
    });
</script>

API

public class ValuesController : ApiController
{
    private NotifEntities context = new NotifEntities();
    [HttpPost]
    public HttpResponseMessage SendNotification(NotifModels obj)
    {
        NotificationHub objNotifHub = new NotificationHub();
        Notification objNotif = new Notification();
        objNotif.SentTo = obj.UserID;
        context.Configuration.ProxyCreationEnabled = false;
        context.Notifications.Add(objNotif);
        context.SaveChanges();
        objNotifHub.SendNotification(objNotif.SentTo);
        //var query = (from t in context.Notifications
        //             select t).ToList();
        return Request.CreateResponse(HttpStatusCode.OK);
    }
}

Modify Hub

We need to add additional methods in our Hub class.

private NotifEntities context = new NotifEntities();
// Logged Use Call
public void GetNotification()
{
    try
    {
        string loggedUser = Context.User.Identity.Name;
        // Get TotalNotification
        string totalNotif = LoadNotifData(loggedUser);
        // Send To
        UserHubModels receiver;
        if (Users.TryGetValue(loggedUser, out receiver))
        {
            var cid = receiver.ConnectionIds.FirstOrDefault();
            var context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
            context.Clients.Client(cid).broadcaastNotif(totalNotif);
        }
    }
    catch (Exception ex)
    {
        ex.ToString();
    }
}
// Specific User Call
public void SendNotification(string SentTo)
{
    try
    {
        // Get TotalNotification
        string totalNotif = LoadNotifData(SentTo);

        // Send To
        UserHubModels receiver;
        if (Users.TryGetValue(SentTo, out receiver))
        {
            var cid = receiver.ConnectionIds.FirstOrDefault();
            var context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
            context.Clients.Client(cid).broadcaastNotif(totalNotif);
        }
    }
    catch (Exception ex)
    {
        ex.ToString();
    }
}
private string LoadNotifData(string userId)
{
    int total = 0;
    var query = (from t in context.Notifications
                 where t.SentTo == userId
                 select t)
                .ToList();
    total = query.Count;
    return total.ToString();
}

Finally the Hub

public class NotificationHub : Hub
{
    private static readonly ConcurrentDictionary<string, UserHubModels> Users =
        new ConcurrentDictionary<string, UserHubModels>(StringComparer.InvariantCultureIgnoreCase);
    private NotifEntities context = new NotifEntities();
    // Logged User Call
    public void GetNotification()
    {
        try
        {
            string loggedUser = Context.User.Identity.Name;

            // Get TotalNotification
            string totalNotif = LoadNotifData(loggedUser);
            // Send To
            UserHubModels receiver;
            if (Users.TryGetValue(loggedUser, out receiver))
            {
                var cid = receiver.ConnectionIds.FirstOrDefault();
                var context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
                context.Clients.Client(cid).broadcaastNotif(totalNotif);
            }
        }
        catch (Exception ex)
        {
            ex.ToString();
        }
    }
    // Specific User Call
    public void SendNotification(string SentTo)
    {
        try
        {
            // Get TotalNotification
            string totalNotif = LoadNotifData(SentTo);

            // Send To
            UserHubModels receiver;
            if (Users.TryGetValue(SentTo, out receiver))
            {
                var cid = receiver.ConnectionIds.FirstOrDefault();
                var context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
                context.Clients.Client(cid).broadcaastNotif(totalNotif);
            }
        }
        catch (Exception ex)
        {
            ex.ToString();
        }
    }
    private string LoadNotifData(string userId)
    {
        int total = 0;
        var query = (from t in context.Notifications
                     where t.SentTo == userId
                     select t)
                    .ToList();
        total = query.Count;
        return total.ToString();
    }
    public override Task OnConnected()
    {
        string userName = Context.User.Identity.Name;
        string connectionId = Context.ConnectionId;

        var user = Users.GetOrAdd(userName, _ => new UserHubModels
        {
            UserName = userName,
            ConnectionIds = new HashSet<string>()
        });

        lock (user.ConnectionIds)
        {
            user.ConnectionIds.Add(connectionId);
            if (user.ConnectionIds.Count == 1)
            {
                Clients.Others.userConnected(userName);
            }
        }
        return base.OnConnected();
    }
    public override Task OnDisconnected(bool stopCalled)
    {
        string userName = Context.User.Identity.Name;
        string connectionId = Context.ConnectionId;

        UserHubModels user;
        Users.TryGetValue(userName, out user);

        if (user != null)
        {
            lock (user.ConnectionIds)
            {
                user.ConnectionIds.RemoveWhere(cid => cid.Equals(connectionId));
                if (!user.ConnectionIds.Any())
                {
                    UserHubModels removedUser;
                    Users.TryRemove(userName, out removedUser);
                    Clients.Others.userDisconnected(userName);
                }
            }
        }
        return base.OnDisconnected(stopCalled);
    }
}

Output

Hope this will help.