Retrieving SignalR connectionId on Web API calls

Question

I have the following constellation:

I am using a asp.net core web api project which also includes a HubContext. The first thing a user has to do is to make an api call to my UsersController : BaseController . Here he/she calls the api/login route passing the according credentials. The return value of the Login() function is a JwtBearerToken, which the user from then on uses for all other api calls.

Once the token has been issued, the user (Client) establishes a SignalR connection over my ConnectionHub : Hub .

So far everything works well, the user gets authenticated using the token when calling api methods and I also can track the according Session state inside the scope of my ConnectionHub .

Now I have to retrieve the users (SignalR) session id whenever he/she makes an api call.

ie When the user calls a method in my UsersController I want to do something like this:

[HttpGet]
public ActionResult<List<User>> GetAll()
{
    // Here I want to retrieve the (SignalR) session id of the user calling this method.
    return Ok( userRepository.GetAllUsers() );
}

So far the only idea I have is to make the user send his SignalR-SessionId with the according api call, but what I'd like to achieve is to read the Id on the server side. How can I achieve this?

Answer 1

According to the Microsoft documentation , it is not possible to get the user's connectionId outside the hub (eg in a controller):

When hub methods are called from outside of the Hub class, there's no caller associated with the invocation. Therefore, there's no access to the ConnectionId , Caller , and Others properties.

---

However, you can get the users with JavaScript by calling a hub method. Here you have access to the connectionId and to the database using your repository (make sure it is available via Dependency Injection).

I don't know what you want to do with the user's exactly, but you can simply return the users in the hub method and do something with the connectionId .

YourHubClass.cs

public Task GetAllUsers()
{
    // Get the ConnectionId
    var connectionId = Context.ConnectionId;

    // Get the users list
    var users = userRepository.GetAllUsers(); 

    // ...

    return Clients.User(user).SendAsync("UserListRequested", users);
}