Sending user notifications in ActiveRecord callbacks?

rubyonrails-talk
1

I am confused about sending emails/push notifications/SMS inside of activerecord callbacks.

I got the idea from DHH’s series On Writing Software Well, episode 2, from 2018, where he showed a basecamp Mention class that does after_commit :deliver which delivers emails and push notifications.

https://youtu.be/M3JPTOTqsnE?t=1087

That seems like a great way to structure stuff, and I immediately went out and created a Reminder model that did the same thing.

But then I found some other, slightly older, posts from DHH that said that emails should not go in activerecord callbacks.

https://news.ycombinator.com/item?id=7336185

https://dhh.dk/2012/emails-are-views.html

https://dhh.dk/posts/43-think-of-emails-as-views-delivered-through-smtp

Was this just a change in 37signals’ writing style from the early 2010s to 2018 when that video came out? Or is the guidance still to try as best as you can to keep any user facing communications inside a controller, and the Mention class just needed to deliver inside of a callback because mentions as a whole are a side concern of recordings, and it would be worse to try to force that mention#deliver into the recordings controller?

2

I think the distinction is more about coupling than callbacks themselves. Sending notifications directly from models can become messy if everything starts triggering side effects. Using after_commit for clearly defined domain events like mentions or reminders can work well, especially with jobs. For general emails, keeping delivery logic separate usually makes the code easier to maintain.