One of my sites is static in the sense that the content is almost never updated. It was initially handcrafted with HTML+CSS+javascript and ran for more than 15 years with no need for maintenance! A few years ago I re-built the site with Rails with some more features, but I struggle with the need to keep up with the new versions of Rails; the initial build was with Rails 3, then I updated to Rails 4 and more recently to Rails 5 - updates necessary just to keep the site up and running. As much as I like Rails, I really don't want to spend time on updates on this particular site, and am thinking of using a static site generator to rebuild the site, but I'm not sure if they can handle my data structures.
The application involves just 8-9 models classes (and MySQL-tables), but with foreign keys to handle has_many and has_and_belongs_to_many relationships. I could export my database to JSON or YAML with id attributes for all records, but I wonder if static site generators like Middleman or Jekyll will be capable of handling these relationships. I quick look through tutorials only shows very simple data structures involving key-value.