ruby 的 though

class FinanceBankAccount < ActiveRecord::Base
  has_many :rels, class_name: 'FinanceBankAccountRel', foreign_key: 'account_id'
  
  has_many :companies, through: :rels, source_type: 'Company', source: :rel, class_name: "Company"
  
  has_many :users, through: :rels, source_type: 'User', source: :rel
end

 赋值：
 @account = FinanceBankAccount.find(params[:account_id])
 @account.company_ids = params[:company_ids].split(',')

＃ INSERT INTO `finance_bank_account_rels` (`account_id`, `rel_type`, `rel_id`) VALUES (14, 'Company', 10852)