Install Rails 3.1 beta with RVM gemsets (a public service announcement)

Last summer, as the early releases of Rails 3.0 began rolling out, I shared how to use RVM to create sandboxes for experimenting with new versions of gems. Fast forward to now—Rails 3.1 is coming our way soon, with some major changes under the hood. These changes are well documented and debated elsewhere, so I won’t get into them here. Once again, there’s no need to wait until 3.1 goes final to see what’s different. Here’s a quick rundown of how to install your own Rails 3.1 sandbox.

First, if you haven’t updated RVM in awhile, it doesn’t hurt to do so now.

  $ rvm update

At this writing, RVM is at version 1.6.5. Don’t forget, you’ll need to open a new terminal window to begin using the new version.

Create a gemset for the beta software:

  $ rvm gemset create rails31beta

Switch to the newly-minted gemset with

  $ rvm use @rails31beta

Now install Rails 3.1 beta:

  $ gem install rails --pre

and create a test application:

  $ rails new mytestapp

We’re almost done. Next create a .rvmrc file to tell RVM which gemset to use in the new application. Note that I’m using Ruby 1.9.2, which I believe is now a requirement in Rails 3.1.

  $ echo "rvm use 192@rails31beta" > mytestapp/.rvmrc

Open the application’s directory, run bundle to install the default gems, and you’re off to the races.

  $ cd mytestapp
  $ bundle

As you look around the application structure, take a look at your Gemfile and the new assets directory inside app/. This is where most of the new features that will affect Rails developers at all levels are located.

Where to go from here?

• There are plenty of jQuery tutorials out there; I don’t have one in particular I recommend over others. This will really only affect you if you use the Prototype/scriptaculous Javascript framework in your Rails apps.
• The Sass tutorial should get you up and running with replacing your CSS. I’ve been using Sass for awhile now and love it—if you haven’t checked it out yet, you owe it to yourself to do so.
• Charles Max Wood at Teach Me To Code has been showing the basics of CoffeeScript in his screencasts. I will admit to being kind of green in this area, but am looking forward to getting Javascript functionality in my apps without having to deal with old-school RJS.