Code example to reproduce the issue "ActiveRecord, find by polymorphic attribute" http://stackoverflow.com/q/14753611/316700

.gitignore

.rvmrc
polymorphic.sqlite

.rvmrc

rvm use --create ruby-1.9.3-p286@polymorphic_where

.rvmrc.example

rvm use --create ruby-1.9.3_p286@polymorphic_where"

Gemfile

source :rubygems

gem "activerecord"
gem "sqlite3"

Gemfile.lock

GEM
  remote: http://rubygems.org/
  specs:
    activemodel (3.2.11)
      activesupport (= 3.2.11)
      builder (~> 3.0.0)
    activerecord (3.2.11)
      activemodel (= 3.2.11)
      activesupport (= 3.2.11)
      arel (~> 3.0.2)
      tzinfo (~> 0.3.29)
    activesupport (3.2.11)
      i18n (~> 0.6)
      multi_json (~> 1.0)
    arel (3.0.2)
    builder (3.0.4)
    i18n (0.6.1)
    multi_json (1.5.0)
    sqlite3 (1.3.7)
    tzinfo (0.3.35)

PLATFORMS
  ruby

DEPENDENCIES
  activerecord
  sqlite3

polymorphic_where_test.rb

require "active_record"
require "minitest/unit"
require "minitest/autorun"

ActiveRecord::Base.establish_connection(
  :adapter  => "sqlite3",
  :database => "#{File.dirname(__FILE__)}/polymorphic.sqlite"
)

ActiveRecord::Schema.define :version => 0 do
  create_table :users, :force => true do |t|
  end

  create_table :events, :force => true do |t|
    t.integer :historizable_id
    t.string :historizable_type
  end
end

class Event < ActiveRecord::Base
  belongs_to :historizable, :polymorphic => true
end

class User < ActiveRecord::Base
  has_many :events, :as => :historizable
end

class PolymorphicWhereTest < MiniTest::Unit::TestCase
  def test_polymorphic_where
    user = User.create!
    event = Event.create!(:historizable => user)

    assert_equal(event, Event.where(:historizable_id => user.id, :historizable_type => user.class.name).first)
    assert_equal(event, Event.where(:historizable => user).first)
  end
end