polymorphism_test.rb

gem 'rails', "~> 3.2"
gem 'squeel', "~> 1.1"
gem 'sqlite3'

require "active_record"
require "squeel"

ActiveRecord::Base.establish_connection adapter: "sqlite3", database: ":memory:"

class A < ActiveRecord::Base
  belongs_to :poly, :polymorphic => true
end

class B < ActiveRecord::Base
  has_many :c, :as => :poly
  has_many :xxx, :class_name => "C", :as => :poly
end

class C < ActiveRecord::Base
  belongs_to :poly, :polymorphic => true
end

class E < ActiveRecord::Base
end


puts A.joins{[poly(B).xxx, poly(E).outer]}.where{poly(B).xxx.column.in(["value1","value2"])}.debug_sql