Qiita:58ab6409f0da60a326e3 Squeelを使った実装

58ab6409f0da60a326e3.rb

require 'active_record'
require 'active_support'
require 'squeel'
require 'minitest/autorun'
require 'logger'
require 'pry'

db_name = 'qiita_58ab6409'

ActiveRecord::Base.establish_connection adapter: 'mysql2', database: 'mysql', host: 'localhost'
ActiveRecord::Base.connection.drop_database db_name rescue nil
ActiveRecord::Base.connection.create_database db_name
ActiveRecord::Base.connection.close
ActiveRecord::Base.establish_connection adapter: 'mysql2', database: db_name, host: 'localhost'

ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table 'users', force: true do |t|
    # t.integer "user_id" # user_id -> id に変更している
    t.integer "period_id"
    t.string "hoge_type"
  end
  create_table "user_balances", force: true do |t|
    t.integer "period_id"
    t.integer "user_id" # employee_id?
    t.integer "amount"
  end
  create_table "user_insurances", force: true do |t|
    t.integer "period_id"
    t.integer "user_id" # employee_id?
    t.string "user_type"
  end
end

class UserBalance < ActiveRecord::Base
  belongs_to :user
end

class UserInsurance < ActiveRecord::Base
  belongs_to :user
end

class User < ActiveRecord::Base
  has_many :user_balances
  has_many :user_balance_with_same_period,
    -> { where { period_id == users.period_id } },
    class_name: 'UserBalance'

  has_many :user_insurances
  has_many :user_insurance_with_same_period,
    -> { where { period_id == users.period_id } },
    class_name: 'UserInsurance'


  # [注意]
  # Originalでは employee_id となっている所を user_id に変更している
  # また、user.user_id を user.id に変更している
  #
  # 以下SQLが生成される
  #
  # SELECT
  #     `users`.`id`
  # FROM
  #     `users`
  #     LEFT OUTER JOIN
  #         `user_balances`
  #     ON  `user_balances`.`user_id` = `users`.`id`
  #     AND `user_balances`.`period_id` = `users`.`period_id`
  #     LEFT OUTER JOIN
  #         `user_insurances`
  #     ON  `user_insurances`.`user_id` = `users`.`id`
  #     AND `user_insurances`.`period_id` = `users`.`period_id`
  # WHERE
  #     `users`.`hoge_type` != 'A'
  # AND `user_balances`.`amount` > 0
  # AND `user_insurances`.`user_type` = 'B'
  def self.squeel_hogehoge_user_ids
    User
      .joins { user_balance_with_same_period.outer }
      .joins { user_insurance_with_same_period.outer }
      .where.not(hoge_type: 'A')
      .where { user_balances.amount > 0 }
      .where { user_insurances.user_type == 'B' }
      .pluck(:id)
  end
end

class CheckEagerLoad < MiniTest::Unit::TestCase
  def setup
  end

  def teardown
    User.delete_all
    UserBalance.delete_all
    UserInsurance.delete_all
  end

  def test_original_hogehoge_user_ids
    # pryでsqlをチェック
    binding.pry
    User.squeel_hogehoge_user_ids
  end
end