The cache_digests gem (also included in Rails 4) will automatically add a digest to the fragment cache key based on the template. If a template changes the cache will auto-expire. But watch out for the gotchas!

RubyGems can make it easy to add a feature to a Rails application, but it can also cause headaches down the road. Here I give some tips on researching gems to decide which one to choose, or when to do it from scratch.

There are several gems to help implement tags in a Rails app. Here I show you how to integrate acts-as-taggable-on and then show how to do it from scratch.

FnordMetric allows you to chart events in real time. This is great for keeping track of user activity in your Rails app as demonstrated in this episode.

JRuby is a polished and stable Ruby implementation. Here I show the basics of setting it up and executing Java from within Ruby. I also see how it compares with MRI at running threads.

Learn how to do extensive image manipulation with the ImageMagick commands. Also learn how RMagick can be used in combination with CarrierWave to process uploaded images.

Bullet will notify you of database queries that can potentially be improved through eager loading or counter cache column. A variety of notification alerts are supported.

Ransack allows you to easily build complex search forms. It also helps in adding sortable links and building a dynamic advanced search page.

MiniProfiler allows you to see the speed of a request conveniently on the page. It also shows the SQL queries performed and allows you to profile a specific block of code.

Sidekiq allows you to move jobs into the background for asynchronous processing. It uses threads instead of forks so it is much more efficient with memory compared to Resque.