When using Rails it's easy to forget there's any other way. Sometimes, however, it's useful to access databases outside of that environment. Luckily, ActiveRecord can be used separately from Rails, and Craig Webster demonstrates how.
The creator of co.mments, Assaf Arkin, a Rails developer, has created a plugin that makes it easy to add a Undo feature to your Rails app. Instead of warning users about things simply let them do it, but give them the choice to undo afterwards. Assaf's plugin doesn't cover all the bases, but it's easy to build upon for creating your own system. For deletion, for example, you'd want to come up with a way to keep the data floating around for a while.
An oldie but a goldie.. Kent Siblev had an issue with his Rails application ballooning to 150 megabytes of memory usage per process. He couldn't figure out where the problem was, so he wrote a small plugin called MemoryLogging to check memory usage on each request (Linux only, I'm afraid). He found his problem within minutes and explains what was going on.
This is a "short" Ruby on Rails reference. It's goal is to give you an overview over the most used functions / methods / classes. It's not a tutorial, but as a handy guide when you already know your way around.
Devin Steffler shows you how to load over 100000 countries, states, and towns into your Rails app's database, from how to get the data to the code to transform the data into database entries.
Stuart Halloway and Justin Gehtland of Relevance LLC have put together an online presentation called AJAX on Rails. It looks at AJAX, its relation to Rails, how Prototype works, and provides lots of great code examples. If you want to brush up on your whole AJAX and Rails knowledge, it's worth looking at. A PDF version is also available.
Basic Ruby
Another new article in Bruce's series shows you how to get DOM-friendly IDs from ActiveRecord. This is a solution nearly all Rails developers have implemented at some time or another:
Bruce Williams has a great set of articles going on on his blog called "Rails Views". Each one looks at a different aspect of Rails' views and templates system and how you can use it in a cool or different way. You are bound to learn something or come up with some ideas on how to make your views more efficient (I sure have!). Here are some of the recent posts in the series:
Tobias Lütke needed to migrate a database from one architecture to another but needed to copy the data across intact. To ensure that the format would be architecture agnostic, he's created a plugin that dumps the data to YAML and then reloads it back into the database at the other end. It's a simple rake task, and Tobi gives quick and easy instructions.
Rodney, the Pin Up Geek, has set out to demystify the routing system in Ruby on Rails. He provides lots of basic code examples and shows you how to use most of the features of routes, like in this example of a requirements based route that only routes when a postal code is included in the URL: