Chapter 9. Advanced Active Record

Active Record is a simple object-relational mapping (ORM) framework compared to other popular ORM frameworks, such as Hibernate in the Java world. Don’t let that fool you, though: Under its modest exterior, Active Record has some pretty advanced features. To really get the most effectiveness out of Rails development, you need to have more than a basic understanding of Active Record—things like knowing when to break out of the one-table/one-class pattern, or how to leverage Ruby modules to keep your code clean and free of duplication.

In this chapter, we wrap up this book’s comprehensive coverage of Active Record by reviewing callbacks, observers, single-table inheritance (STI), and polymorphic models. We also review a little bit of information about metaprogramming and Ruby domain-specific languages (DSLs) as they relate to Active Record.