如何取消订阅redux observable中的内部observable？

Question

In the following epic I am listening to an action$ stream and then also listening to an auth stream authState(app.auth())

export const fetchAuthStatus = action$ =>
      action$.pipe(
        ofType(AUTH_STATUS_CHECKED),
        switchMap(() => authState(app.auth())),
        switchMap(user =>
          user
            ? of({ type: 'SIGNED_IN', payload: user })
            : signIn(googleAuthProvider)
        ),
        catchError(error => console.log('problems signing in'))
      );

It works as expected, the only problem is that if I change the auth status by logging out then the epic fires the signIn() method since user is no longer available.

How do I stop listening to authState(app.auth()) once I have signed in. Where does the unsubscribe logic go in an epic?

Answer 1

Epics are supposed to stay alive as long as your app is running.

You don't complete them, you mute them .

To mute a stream there are a lot of possibilities. For example, windowToggle operator will let you mute your observable by another streams, say, by streams of other events.

Eg you mute the epic while in-between SIGN_IN — SIGN_OUT sequence. And unmute in SIGN_OUT — SIGN_IN period.

Heres an article on different pausing strategies with rxjs .

Hope this helps