检查是否在before_save事件上修改或创建了模型

Question

I want to check if a model is being created in the before_save callback of Rails. I also want to check if it has been modified (when updating).

Thanks

Answer 1

You can use new_record? to see if you have a brand new object and changed? to see if anything has changed:

before_save :pancakes

def pancakes
    if new_record?
        # Not in the database yet.
    elsif changed?
        # Already exists but it has unsaved changes.
    end
end