CODEWITHSUNDEEP
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ShaneKm
ShaneKm

Reputation: 21368

SignalR hub connection StateChanged not working client

Working with .net Core and have setup everything using this tutorial: https://learn.microsoft.com/en-us/aspnet/core/tutorials/signalr?view=aspnetcore-3.1&tabs=visual-studio.

I wanted to be able to use lifetime events based on this tutorial: https://learn.microsoft.com/en-us/aspnet/signalr/overview/guide-to-the-api/hubs-api-guide-javascript-client

However I get:

connection.stateChanged or connection.disconnected is not a function

var connection = new signalR.HubConnectionBuilder().withUrl("/chatHub").build();
connection.start().then(function () {
}).catch(function (err) {
    return console.error(err.toString());
});

connection.stateChanged(function () {
    console.log('in');
});

I would like to detect "disconnected" even on the client.

Upvotes: 1

Views: 6056

Answers (2)

Malcolm Swaine
Malcolm Swaine

Reputation: 2268

To monitor the connection being dropped, I've not had a lot of luck with the onclose method. I assume this is when the server side actually intentionally closes the connection to the client in a controlled manner, rather than the connection dropping.

Instead I use the onreconnecting method along with the withAutomaticReconnect configuration.

this.hubConnection = new signalR.HubConnectionBuilder()
      .withUrl('https://localhost:7142/jobshub')
      .withAutomaticReconnect({
        nextRetryDelayInMilliseconds: _ => {
          return 3000;
        }})
      .build();

...

   this.hubConnection.onreconnecting((e) => {          
      this.connectedToServer = false;
      console.log('signalr connection dropped - reconnecting');
    });

If the hub connection is reconnecting then I know the connection must have dropped and I can respond.

I also handle the reconnected event, so I can then restore functionality back to my app

this.hubConnection.onreconnected(() => {
      this.connectedToServer = true;
      console.log(`signalr connection restored`);
    });

Upvotes: 0

Xueli Chen
Xueli Chen

Reputation: 12725

From the MS Doc on HubConnectionState , there are only 2 states:

  • Disconnected
  • Connected

Those states are exposed through a state property in the connection but there are no states for anything else.

From the what anurse said in this github issue , thestart Promise lets you know when the connection starts and the closed event lets you know it's stopped. They don't have automatic reconnects, so those are the only state transitions.

So you could use the following method as Dennis1679 said above 

connection.onclose(function(){
    console.log('connecition closed');
});

Upvotes: 2

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