Services
Technology Web App Development Mobile App Development Windows App Development Database Development UI/UX Development Cloud Development SEO Digital Marketing Guest Posting Content Writing Artificial Intelligence Data Science ERP Development CRM Development CMS Development LMS Development Business Listing Blockchain Technology Startup Promotion
Products
Data Converter Cleaner TUC - Unit Converter Import Export Survey Manager Tweet Controller
Developer
Article Blog Forum Interview Beginner News Startup Quiz
Users
Career
Apply Job Internship
Pricing
Login Sign Up Get a Quote

interview

home / developersection / interviews / how can you handle user connection and disconnection events in signalr?
Ask Question

How can you handle user connection and disconnection events in SignalR?

Ravi Vishwakarma 512 22 May 2025
c# c#signalr
Updated 22 May 2025
Ravi Vishwakarma
Ravi Vishwakarma

IT-Hardware & Networking

Ravi Vishwakarma is a dedicated Software Developer with a passion for crafting efficient and innovative solutions. With a keen eye for detail and years of experience, he excels in developing robust software systems that meet client needs. His expertise spans across multiple programming languages and technologies, making him a valuable asset in any software development project.

Message

1 Answers

Ravi Vishwakarma
Ravi Vishwakarma 22 May 2025
Report Abuse

In SignalR, you can handle user connection and disconnection events by overriding the virtual methods OnConnectedAsync and OnDisconnectedAsync in your Hub class.

Basic Implementation

public class ChatHub : Hub
{
    // Called when a new client connects
    public override async Task OnConnectedAsync()
    {
        string connectionId = Context.ConnectionId;
        string userId = Context.UserIdentifier;

        Console.WriteLine($"User connected. UserId: {userId}, ConnectionId: {connectionId}");

        // Optionally store user-connection mapping
        // Notify others or update UI

        await base.OnConnectedAsync();
    }

    // Called when a client disconnects
    public override async Task OnDisconnectedAsync(Exception exception)
    {
        string connectionId = Context.ConnectionId;
        string userId = Context.UserIdentifier;

        Console.WriteLine($"User disconnected. UserId: {userId}, ConnectionId: {connectionId}");

        // Clean up user-connection mapping
        // Notify others or update UI

        await base.OnDisconnectedAsync(exception);
    }
}

Notes

1. User Identification

  1. Context.ConnectionId: Unique for each connection.
  2. Context.UserIdentifier: Set automatically if authentication is configured.
  3. Context.User: Full ClaimsPrincipal for the user.

To customize UserIdentifier, use a custom IUserIdProvider:

public class CustomUserIdProvider : IUserIdProvider
{
    public string GetUserId(HubConnectionContext connection)
    {
        // Return a custom ID, e.g., username from claims
        return connection.User?.FindFirst("sub")?.Value;
    }
}

Register it:

services.AddSingleton<IUserIdProvider, CustomUserIdProvider>();

2. Common Use Cases

  1. Tracking online/offline status
  2. Managing user groups
  3. Cleaning up resources or subscriptions
  4. Broadcasting status changes (e.g., “User X has joined”)

Example: Notifying Others

public override async Task OnConnectedAsync()
{
    await Clients.Others.SendAsync("UserConnected", Context.UserIdentifier);
    await base.OnConnectedAsync();
}

public override async Task OnDisconnectedAsync(Exception exception)
{
    await Clients.Others.SendAsync("UserDisconnected", Context.UserIdentifier);
    await base.OnDisconnectedAsync(exception);
}
advertising