UUID primary keys in Rails 3

Gemfile

# Gemfile
…
gem 'uuidtools' 
…

migrations.rb

# db/migrate/20110422210841_create_sites.rb
# 1.  :id => false
# 2.  :uuid 
#
class CreateSites < ActiveRecord::Migration
  def self.up
    create_table(:sites, :id => false) do |t|
      t.string :uuid, :limit => 36, :primary => true
      t.timestamps
    end
  end

  def self.down
    drop_table :sites
  end
end

site.rb

# app/models/site.rb
class Site < ActiveRecord::Base
  include Extensions::UUID
end

uuid.rb

# app/models/extensions/uuid.rb
#
module Extensions
  module UUID
    extend ActiveSupport::Concern

    included do
      # old rails versions 
      set_primary_key 'uuid'
      # later rails versions, untested:
      # self.primary_key = 'the_name'

      before_create :generate_uuid
      
      def generate_uuid
        self.id = UUIDTools::UUID.random_create.to_s
      end
    end
  end
end

I was using this approach for a long time, but now after upgrading it stops working. I also get

Got this when i did run some spec:
DEPRECATION WARNING: Calling set_primary_key is deprecated. Please use self.primary_key = 'the_name' instead.

and morover i get new error

uninitialized constant RSpec::Matchers::Extensions::UUID

in rspec tests when trying to use routing paths, which used to work.

Is there a update to this approach? (hopefully not radically different]

@warmwaffles you should probably read more about UUIDs and primary key uniqueness ;-)

When possible and you don't mind the database lock-in, do it in the database.

Sometimes, when you have an async API that pushes customer data e.g. on a MQ/redis. You need to generate and return the UUID on the customer-facing system. You can't wait/block for the full, async database round-trip.

If you are using Ruby 1.9.3+ you can just call SecureRandom.uuid. You also don't need gem 'uuidtools'.

Thanks for this.

For Rails 3.1+ check ActiveUUID