确定ActiveRecord对象是否为新

Question

如何检查ActiveRecord对象是新对象还是已经存在？

Answer 1

ActiveRecord对象生命周期:

1. 新纪录

item = Item.new
item.new_record? #=> true

2. 坚持

item.save
item.persisted? #=> true

3. 改变

item.name = "other"
item.changed? #=> true

4. 销毁

item.destroy
item.destroyed? #=> true

Answer 2

#new_record? 这样做:

object.new_record?