In this episode, we build our associations and organize our mathematical business logic.

In this episode, we look at 3 different ways of importing data into a Rails application; each having their own use cases, drawbacks and benefits.

Using polymorphic associations, we can have comments assigned to a post as well as comments assigned to other comments.

Abstract super class that provides a thread-isolated attributes singleton, which resets automatically before and after each request. This allows you to keep all the per-request attributes easily available to the whole system.

Store multiple attributes and values using a text column. Not for everyday use, but has situations where it can save on the number of columns and/or models needed to accomplish a task.