Rails 3 Cliff Notes, Part 1: getting started

1. Requires Ruby 1.8.7 or higher, but Ruby 1.9.2 is very stable and you should use it for new projects (unless you deploy on Heroku). Use rvm to remain sane when switching between new and old projects. By creating a .rvmrc file, rvm will automatically switch you to the right version of Ruby and set of gems when you cd into the directory.
2. Heroku requires 1.8.7 for Rails 3. To create a heroku app for rails 3, you need to use the “bamboo” stack

   heroku create --stack bamboo-ree-1.8.7
   

3. You must use bundler which means that the only gems that Rails will use are the ones declared in your Gemfile. Very cool.
   • I plan to use Heroku, so I want to make sure that I’m only using sqlite3 in development and test.
   • I like rspec, so I also add it to my Gemfile (added to development as well as test, so I can use generators
   • Update: if you scaffold and rspec generates view specs, it will use webrat steps, but there is no gem dependency, you need to add webrat to the Gemfile
4. No more script/console, use the rails command for everything
5. Set up the test framework that you like first, then the rails generators will create the correct corresponding tests, specs, or whatever

$ rvm install 1.9.2
$ rvm use 1.9.2
$ rvm gemset create rails3
$ rvm use 1.9.2@rails3
$ rails new myapp
$ cd myapp
$ echo "rvm use 1.9.2@rails3" >> .rvmrc
$ vi Gemfile   # add the following to your gemfile 
group :development, :test do
 gem 'sqlite3-ruby', :require => 'sqlite3'
 gem "rspec-rails", ">= 2.0.0.beta.22"
 gem "webrat"      # currently generated view specs require this
end
$ bundle install
$ rails generate rspec:install
$ rails generate scaffold note title:string content:text
$ rake db:migrate
$ rails server

Good resources

• Rails 3.0 release notes