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Rails without ActiveRecord

Posted by Doug Wed, 08 Aug 2007 13:02:00 GMT

It’s supposed to be easy to turn off ActiveRecord and have a database-less app. The word is it’s possible in rails 1.1.x, but not with vanilla rails 1.2.x. To get your environment to load with rails 1.2, you still need a database.yml and the database created (even though it can be empty). That seems a bit silly to me. If you want a database-less app, you don’t want to have to create a database and maintain a connection to that database. There’s two problems I’ve worked around to get a true database-less app with rails 1.2.

Theoretically all you have to do is set

Rails::Initializer.run do |config|
  config.frameworks -= [:active_record]
end

The first problem is whiny nil requires ActiveRecord. By default config.whiny_nils is set to false. However, both config/environments/development.rb and config/environments/test.rb both explicitly set it to true. What I did was just comment out those assignments in the respective files. Besides detecting when you call ActiveRecord methods on nil, whiny_nil will also detect when you call Array methods on nil. By turning off whiny_nil, you loose the ability to easily detect when you’re treating nil like an Array.

The second problem is that the Rails initializer requires AcriveRecord to load the observers. This is documented in ticket #6795 on the Rails trac. It seems a bit kludgy, but what I did was redefine the load_observers method before I run the initializer in my environment.rb:

require File.join(File.dirname(__FILE__), 'boot')

module Rails
  class Initializer
    def load_observers
      ActiveRecord::Base.instantiate_observers if 
          configuration.frameworks.include?(:active_record)
    end
  end
end

Rails::Initializer.run do |config|
...

There are several reasons for wanting a database-less rails app. The ticket above references using something like CVS or Subversion as a datastore and using rails’ ActionPack to drive an interface. I’ll get into my own uses in another post soon.