How to reuse Promise<void> after using it once in my Angular service? - promise

Question

I have a problem with my Angular Promise<void> in one of my services.
The service establishes SignalR connection with the server's hub. And I am waiting with broadcasting to the hub for connection to be established:
export class SignalRService {
private hubConnection: signalR.HubConnection;
private url = environment.apiUrl + 'messageHub';
private thenable: Promise<void>;
public startConnection = (): void => {
if (!this.hubConnection) {
const token = this.auth.getAuth().token;
this.hubConnection = new signalR.HubConnectionBuilder()
.withUrl(this.url, { accessTokenFactory: () => token })
.build();
this.startHubConnection();
this.hubConnection.onclose(() => this.connectionHubClosed());
}
};
private startHubConnection() {
this.thenable = this.hubConnection.start();
this.thenable
.then(() => console.log('Connection started!'))
.catch((err) => console.log('Error while establishing connection :('));
}
public broadcastGameState = (): void => {
this.thenable.then(() => {
const name = this.auth.getAuth().displayName;
let message = this.game.getGame();
this.hubConnection
.invoke('SendMessage', message)
.catch((err) => console.error(err));
});
};
But after I will close my connection with:
public stopConnection = (): void => {
if (this.hubConnection) {
this.hubConnection.stop();
}
};
and use again my service, I can not use my thenable anymore, and broadcastGameState does not wait anymore for it, throwing an error:
Error: Cannot send data if the connection is not in the 'Connected'
State.
I do not understand why?

Answer 1

xxh you got your point and made me thinking, so I found the problem :) After calling:
public stopConnection = (): void => {
if (this.hubConnection) {
this.hubConnection.stop();
}
};
on connection close is called:
private connectionHubClosed(): void {
//trigerred when lost connection with server
alert('todo: SignalR connection closed');
}
BUT this.hubConnection is still with assigned value, so because of if (!this.hubConnection) new this.thenable was skipped.