One of Rails' best conventions for DRYing up your code is ActiveSupport::Concern. Kingsley Silas shows you how to use it.
William Kennedy shows a technique to dynamically chain many ActiveRecord scopes together to clean up your controller code.
Ilya Bodrov-Krukowski runs through several common Rails performance problems, showing how to find them via Skylight, and how to fix them.
Ilya Bodrov-Krukowski shows you how to do nested forms and attributes in Rails with the Cocoon gem.
William Kennedy uses a simple example of making integers into Roman numerals to show off Ruby metaprogramming.
Vahob Rasti uses Dropzone.js to equip a Rails application with multiple file, asynchronous upload.
Glenn Goodrich takes another deep dive into the world of Bundler, this time focusing on the utilities that ship with Bundler.
Benjamin Tan Wei Hao takes a quick dive into Crystal, a new programming language that is statically typed and compiled but has Ruby syntax.
William Kennedy demonstrates using SQS and Shoryuken to process queued requests to a third-party API. Very useful