How to collapse multiple notifications into a single one using Firebase?

Question

I have function in Firebase Cloud Functions which is used to send notifications to specific users within my app and has as the notificationContent the following cod

Answer 1

I had this same confusion and realized I misunderstood what collapseKey and tag are for.

collapseKey will limit the number of notifications a client receives while they're offline, tag is what will stack notifications together in the drawer.

So for a typical cloud function, it should look like this:

  const notification = {
    notification: {
      'title': 'Interesting title',
      'body': 'Hello, world'
    },
    'data': {
      'whatever': whatever,
    },
    'android':{
      'collapseKey': collapseKey,
      'priority': 'high',
      'notification': {
        'tag': tag,
      }
    },
    'token': fcmToken
  };

  admin.messaging().send(notification)

Note that the "tag" parameter sits inside of the android notification, not the top-level notification.