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Note: I am working on an e-commerce website where users need to be able to receive messages even if they are offline (the messages would be stored in DB and they can read once the are online).
Do the followings to send message using randomly generated connectionId in secured way:
First add the following classes to track user's connectionIds to understand whether the user is online or offline
public static class ChatHubUserHandler
{
public static ConcurrentDictionary<string, ChatHubConnectionViewModel> ConnectedIds =
new ConcurrentDictionary<string, ChatHubConnectionViewModel>(StringComparer.InvariantCultureIgnoreCase);
}
public class ChatHubConnectionViewModel
{
public string UserName { get; set; }
public HashSet<string> UserConnectionIds { get; set; }
}
Configure the ChatHub as follows
To make the ChatHub secured add [Authorize] attribute on the ChatHub class.
[Authorize]
public class ChatHub : Hub
{
private string UserName => Context.User.Identity.Name;
private string ConnectionId => Context.ConnectionId;
// Whenever a user will be online randomly generated connectionId for
// him be stored here.Here I am storing this in Memory, if you want you
// can store it on database too.
public override Task OnConnected()
{
var user = ChatHubUserHandler.ConnectedIds.GetOrAdd(UserName, _ => new ChatHubConnectionViewModel
{
UserName = UserName,
UserConnectionIds = new HashSet<string>()
});
lock (user.UserConnectionIds)
{
user.UserConnectionIds.Add(ConnectionId);
}
return base.OnConnected();
}
// Whenever a user will be offline his connectionId id will be
// removed from the collection of loggedIn users.
public override Task OnDisconnected(bool stopCalled)
{
ChatHubConnectionViewModel user;
ChatHubUserHandler.ConnectedIds.TryGetValue(UserName, out user);
if (user != null)
{
lock (user.UserConnectionIds)
{
user.UserConnectionIds.RemoveWhere(cid => cid.Equals(ConnectionId));
if (!user.UserConnectionIds.Any())
{
ChatHubUserHandler.ConnectedIds.TryRemove(UserName, out user);
}
}
}
return base.OnDisconnected(stopCalled);
}
}
Now use the following model class to store the message to the database. You can also customize the message class according to your exact need.
public class Message
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long MessageId { get; set; }
[ForeignKey("Sender")]
public string SenderId { get; set; }
[ForeignKey("Receiver")]
public string ReceiverId { get; set; }
[Required]
[DataType(DataType.MultilineText)]
public string MessageBody { get; set; }
public DateTime MessageSentAt { get; set; }
public bool IsRead { get; set; }
public User Sender { get; set; }
public User Receiver { get; set; }
}
Then in the Message Controller:
This is just an example code. You can customize the code according to your exact need.
[HttpPost]
public async Task<ActionResult> SendMessage(string messageBody, string receiverAspNetUserId)
{
string loggedInUserId = User.Identity.GetUserId();
Message message = new Message()
{
SenderId = loggedInUserId,
ReceiverId = receiverAspNetUserId,
MessageBody = messageBody,
MessageSentAt = DateTime.UtcNow
};
_dbContext.Messages.Add(message);
_dbContext.SaveChangesAsync();
// Check here if the receiver is currently logged in. If logged in,
// send push notification. Send your desired content as parameter
// to sendPushNotification method.
if(ChatHubUserHandler.ConnectedUsers.TryGetValue(receiverAspNetUserId, out ChatHubConnectionViewModel connectedUser))
{
List<string> userConnectionIds = connectedUser.UserConnectionIds.ToList();
if (userConnectionIds.Count > 0)
{
var chatHubContext = GlobalHost.ConnectionManager.GetHubContext<ChatHub>();
chatHubContext.Clients.Clients(userConnectionIds).sendPushNotification();
}
}
return Json(true);
}
Now question is what if the message was sent whenever the receiver was offline?
Okay! In this case you can handle the push notification in two ways! calling a ajax method or SignalR Hub method as soon as the receiver is online to bind the notifications. Another method is using partial view for notification area in layout page. I personally prefer using partial view for notification area.
Hope this will help you!
