active_record_inherit_assoc_parent_inherit_child_issue.rb

require 'active_record'
require 'pg'
require 'active_record_inherit_assoc'

# set up database
PG_SPEC = {
  adapter:  'postgresql',
  database: 'inherit_test_db'
}

ActiveRecord::Base.establish_connection(PG_SPEC.merge('database' => 'postgres', 'schema_search_path' => 'public'))
ActiveRecord::Base.connection.drop_database PG_SPEC[:database] rescue nil
ActiveRecord::Base.connection.create_database(PG_SPEC[:database])
ActiveRecord::Base.establish_connection(PG_SPEC)

# Set active record logger to STDOUT to see executed SQL
ActiveRecord::Base.logger = Logger.new(STDOUT)

# define migration to set schema
class CreateModels < ActiveRecord::Migration
  def self.change
    create_table :users do |t|
      t.integer :some_attr

      t.timestamps
    end

    create_table :accounts do |t|
      t.integer :user_id
      t.integer :some_attr

      t.timestamps
    end
	end
end

# run migrations
CreateModels.change

# define models and populate db
class User < ActiveRecord::Base
  has_one :account, inherit: [:some_attr]
end

class Account < ActiveRecord::Base
  belongs_to :user
end

user    = User.create!(some_attr: 1)
account = Account.create!(user_id: user.id, some_attr: 1)

user.account # dirty the statment cache

user_2    = User.create!(some_attr: 2)
account_2 = Account.create!(user_id: user_2.id, some_attr: 2)

puts user_2.account.inspect # nil as the SELECT statement uses the `some_attr` value from the previous call.