How to catch 401 Unauthorized from SignalR after token expired

Question

I have built an page that gets real-time data from my azure functions backend via SignalR. Lets say i stay on the page, watching the data for 1 hour, and i might get a disconnect, the signalr client will try to reconnect automatically, this works fine. But when it tries to reconnect the jwt token might have expired and a 401 is throw from the signalr client.

Is there any way to catch this 401 from the signalr client when a reconnect is fired?

Many people seems to use.onclose() but will not work for me, or fetching a new jwt token every time they connect, i guess this might be the way i need to proceed, but i prefer if it would be possible to catch it instead, that would be a better fix in my opinion.

var connection = new signalR.HubConnectionBuilder()
                .configureLogging(signalR.LogLevel.Information)
                .withUrl(config.default.hostname + "/api/v1/core/signalr",
                    { accessTokenFactory: () => store.state.accessToken })
                .withAutomaticReconnect([0, 0, 10000])
                .build();

connection.start();

Hope you understand what I'm looking for here! Cheers!

Answer 1

That is why on the { accessTokenFactory: () => store.state.accessToken } you should pass a function that will refresh the token. So when the token expires, it will automatically check for new token from this method. So don't store the token in store.state.accessToken ...