Michael Herold

In the last article, we saw how to use the ActiveRecord Attributes API to make Ruby on Rails models more communicative. The two explicit benefits of doing so from that article were a more discoverable data model and a uniform way of defining different types of attributes. The article also hinted at using richer data types to model attributes. That is the topic of this article.

ActiveRecord is the powerful object-relational mapper at the heart of Ruby on Rails. By default, it gives you tools to quickly and easily create new database tables and map them to domain models. It follows the ethos of “convention over configuration” that David Heinemeier Hansson coined with the release of Rails. As such, with little application code, you get a powerful, database-backed model that Just Works™.

Ruby on Rails has an easy-to-use cookie store for managing state between requests. It has affordances for storing clear-text values, tamper-proof signed values, and encrypted values. I previously showed how you can make good use of encrypted values for handling ActionCable authentication. However, there is a case where you might end up with duplicate cookies in Ruby on Rails applications.

Arel, the SQL syntax tree constructor library backing ActiveRecord, allows you to express your SQL queries without the use of fragments. ActiveRecord uses it internally to represent a variety of queries. It does this transparently using the traditional where(key: value) syntax that we’ve seen since the early days of Rails.

When designing your domain model for an application, the natural solution might end up using a nil to model the absence of a value. In these cases, you might need to reach for null-based ordering within your database. When you’re writing a Ruby on Rails application, you’re most likely going to use ActiveRecord as the interface to your database. While ActiveRecord supports most queries out-of-the-box, sometimes you have to go off the beaten path.

Account impersonation is when you allow accounts (usually privileged accounts, e.g. support staff or developers) to operate your Rails application as if they are the owner of another account entirely. It’s a helpful feature to have when diagnosing issues that your customers write in about. There are plenty of gems that implement impersonation for your Rails controllers, but I wasn’t able to turn up any suggestions for implementing this for ActionCable.

Software teams often cite code reviews as a primary means for ensuring quality and reducing bugs in their code. However, without high quality reviews, the efficacy of this practice is questionable. In most places that I’ve worked, a change requires only one code review (either through necessity due to team size or through informal norms). When this is the case, the code review becomes a taxing process where, if you’re not on your game, bugs or maintainability issues can start to leak into production. This means that it often falls to the senior engineers to do code reviews. However, relying entirely on the seniors means that they become a bottleneck in the process. When it comes to “dangerous” changes like Rails database migrations, the bottleneck of relying on a small subset of the team can mean that velocity drops. Or, to keep up velocity, you make code reviews less stringent and quality drops.

Sometimes, designers will mock-up an extremely usable page that they’ve thought about and tested. Once they’re done and they bring it to you to implement, you look at it and think, “how on Earth can I do that efficiently?” One such case happened at work recently.

Sometimes, I find myself working across several branches helping different teammates with their stories. Often, these branches use Rails migrations to easily manage the database changes that need to be made to support the work. This means that I end up running migrations from many different branches. Because I am human, I often forget to roll those migrations back before switching branches. When a destructive migration has to happen as part of a branch, it leaves me in a situation where I have several migrations that I need to roll back at any given time. In addition, they might be interleaved with migrations that exist on the master branch if it’s a longer-running branch.