Rails 3 生成迁移 - 没有向上或向下方法
刚刚学习 Rails，正在进行迁移，一切都从逻辑上开始，直到我在代码中遇到了一些奇怪的事情；
rails generate migration AddRegionToSupplier
上面生成了一个迁移文件，其中仅包含“def change”方法。
我用谷歌搜索了一下，发现这正是应该发生的事情；
http://guides.rubyonrails.org/migrations.html
我希望它会生成“def up”并且“def down”方法，以便回滚迁移。我在这一代人中是否做错了什么，或者我错过了一些明显的事情？
Just learning rails, am on to migrations and it all started off pretty logically until I hit something odd going on in the code;
rails generate migration AddRegionToSupplier
The above produces a migration file with only a "def change" method in it.
I googled this and found that this is exactly what is supposed to happen;
http://guides.rubyonrails.org/migrations.html
I would have expected it to generate a "def up" and "def down" method, so that the migration could be rolled back. Have I done something wrong in the generation or am I missing something obvious?
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从您粘贴的链接：
因此，看起来您不必担心
def self.down，因为 Rails 现在足够智能，知道如何将其回滚。From the link you pasted:
So it looks like you don't have to worry about having a
def self.downas Rails is now smart enough to know how to roll it back.