I did a bunch of work in rails prior to the 3.0 days ( probably around 2013 or so), but then switched domains to work more in data engineering. When I came back to it to scratch an itch for some pet projects, I barely recognized it. I felt completely lost. Life moved pretty fast, I guess. Are there any good resources out there for someone from the 2.x days to get back to speed?
For what it’s worth, the 2->3 update was by far the most consequential; they merged in Merb, rewrote how routes and controllers worked, and completely flipped expectations on how JS and views should work. Rails 3->6 has had far fewer major user-facing architectural changes, and consisted mostly of new tools and APIs. A lot of stuff they added used to be handled by gems - password hashing, attachments, background jobs…
Models live in the same spot. Controllers live in the same spot. Your classes generally still inherit from the same stuff, albeit with some additions to the tree like for ApplicationRecord in places where you might previously have inherited directly from ActiveRecord::Base.
The stability is one of my favorite parts of Rails. Its still modern and very usable, but I don't need to relearn it all the time.