Array Attribute for Ruby Model

Create a model with a text field

> rails g model Arches thearray:text
  invoke  active_record
  create    db/migrate/20111111174052_create_arches.rb
  create    app/models/arches.rb
  invoke    test_unit
  create      test/unit/arches_test.rb
  create      test/fixtures/arches.yml
> rake db:migrate
==  CreateArches: migrating ===================================================
-- create_table(:arches)
   -> 0.0012s
==  CreateArches: migrated (0.0013s) ==========================================

edit your model to make the field serialized to an array

class Arches < ActiveRecord::Base
  serialize :thearray,Array
end

test it out

ruby-1.8.7-p299 :001 > a = Arches.new
 => #<Arches id: nil, thearray: [], created_at: nil, updated_at: nil> 
ruby-1.8.7-p299 :002 > a.thearray
 => [] 
ruby-1.8.7-p299 :003 > a.thearray << "test"
 => ["test"]