Sending an email when user has not logged-in to app in a while

Question

I need some suggestions on how to go about implementing sending an email to a user when they haven't been logged in to an app in say 3 days (in javascript). Basically, notifying a user based on their lastLoggedIn status which i'd store in the Database. Any pointers will be appreciated.

Answer 1

You can use Cloud Scheduler to create a job with a pubsub Cloud Function as target, using the same topic.

Use the frequency option to set the 3 days.

Edit:

Or you can use this new feature:

https://firebase.google.com/docs/functions/schedule-functions

exports.scheduledFunction = functions.pubsub.schedule('every 5 minutes').onRun((context) => {
  console.log('This will be run every 5 minutes!');
  return null;
});

Which is basically the same:

When you deploy a scheduled function, the related scheduler job and pub/sub topic are created automatically. The Firebase CLI echoes the topic name, and you can view the job and topic in the GCP Console.

Answer 2

You should write a cron task for your database.

Like, some code that will run everyday @10.00 AM to check whether user's lastLoggedIn is greater that 3 days. Later on you can notify those pooled users.

Check this nodejs mongodb cron thread that will give you an opinion. Hope it helps!