Redux-saga firebase onAuthStateChanged eventChannel

Question

How to handle firebase auth state observer in redux saga?

firebase.auth().onAuthStateChanged((user) => {

});

I want to run APP_START saga when my app starts which will run firebase.auth().onAuthStateChanged observer and will run other sagas depending on the callback.

As I understand eventChannel is right way to do it. But I don't understand how to make it work with firebase.auth().onAuthStateChanged.

Can someone show how to put firebase.auth().onAuthStateChanged in to eventChannel?

Answer 1

You can use eventChannel. Here is an example code:

function getAuthChannel() {
  if (!this.authChannel) {
    this.authChannel = eventChannel(emit => {
      const unsubscribe = firebase.auth().onAuthStateChanged(user => emit({ user }));
      return unsubscribe;
    });
  }
  return this.authChannel;
}

function* watchForFirebaseAuth() {
  ...
  // This is where you wait for a callback from firebase
  const channel = yield call(getAuthChannel);
  const result = yield take(channel);
  // result is what you pass to the emit function. In this case, it's an object like { user: { name: 'xyz' } }
  ...
}

When you are done, you can close the channel using this.authChannel.close().