https://joe11051105.gitbooks.io/you-need-to-know-about-ruby-on-rails/content/activerecord/persisted_vs_new_record.htmlpersisted? vs new_record?Explain  ● persisted? 判斷是否已經存入 database 且不是新增的資料  ● new_record? 判斷是否是新增資料Eaampleuser = User.newuser.new_record?  # trueuser.persisted?   # falseuser = User.firstuser.new_record?  # falseuser.persisted?   # true