Deviseにおいて、複数の認証キー（企業コード、ユーザID、パスワードの組み合わせ）で認証する

User.rb

class User < ActiveRecord::Base
  belongs_to :company
  belongs_to :branch
  belongs_to :shop
 
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :authentication_keys => [:company_code, :user_id]
 
  attr_accessor :company_code
 
  # enable authentication by user_id
  def self.find_first_by_auth_conditions(warden_conditions)
    conditions = warden_conditions.dup
    logger.debug "*************** conditions class ******************"
    logger.debug conditions.to_yaml
 
    company_code = conditions.delete(:company_code)
    company = Company.where(code: company_code).first
    user_id = conditions.delete(:user_id)
 
    logger.debug "company_code: " + company_code
    logger.debug "company: " + company.to_yaml
    logger.debug "user_id: " + user_id
 
    # devise認証を、複数項目(企業ID、及びユーザID)に対応させる
    if company && user_id
      where(conditions).where(["company_id = :company_id AND lower(user_id) = :user_id",
        { company_id: company.id, user_id: user_id }]).first
    else
      where(conditions).first
    end
  end