C#•3d ago

SignalR : Websocket connected twice on connection.

Hello, On my current project (frontend : ReactJS / backend : .NET 9) when I successfully connect to my SignalR hub, it connects twice, as shown per the screenshot. I can't find any clue on the internet of why this is happening. Does someone knows how to solve this ? Thanks.

5 Replies

Ꜳåąɐȁặⱥᴀᴬ•3d ago

are you sure it's not closing and reconnecting?

NaesoOP•3d ago

Nope, it does call OnConnectedAsync twice without calling OnDisconnectedAsync

Ꜳåąɐȁặⱥᴀᴬ•3d ago

i don't really use ReactJS, but if i did probably would need more code to understand what's happening

NaesoOP•3d ago

Honestly there isn't much else on the front-end. https://pastebin.com/bKdeYKqH The little code is the only thing related to websockets. The rest is just pure HTML structure (Ive made the front end by designing what the website should look like first and rn I'm only starting to integrate the buisness logic)

Pastebin

//react imports for constructing the page's HTMLexport default func...

Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time.

NaesoOP•3d ago

I think I may have found a way.

const connection = new HubConnectionBuilder()
    .withUrl('https://localhost:5193/[...]')
    .build();

export default function MyFunction() {
    useEffect(() => {
        connection.start().catch(err => console.error(err));
    });

      return (
        [...]
      );
}

const connection = new HubConnectionBuilder()
    .withUrl('https://localhost:5193/[...]')
    .build();

export default function MyFunction() {
    useEffect(() => {
        connection.start().catch(err => console.error(err));
    });

      return (
        [...]
      );
}

This effectively creates only one connection. If I put the connection builder inside of Effect, it creates two connections. So I have to seperate them like this. Strangely enough, in all examples I could find, both the builder and the start() function should be in the same "useEffect" method. Oh well, if this may help someone else in the future, here goes something that worked for me.

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SignalR : Websocket connected twice on connection.

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