Update nested records in one sql query (active record, ruby on rails)

Question

I'd like to update all user preferences to a default value efficiently. The following works correctly but does not seem good enough:

Employer.find_each do |employer|
  employer.user_preferences.update_all(send_emails: employer.send_emails)
end

Any hints?

Answer 1

我现在无法对其进行测试，但是您可以使用joins ：

UserPreference.joins(:employer).update_all('send_email = employers.send_emails')