添加多态引用的向下迁移是什么？

Question

我有以下迁移但不知道在该down方法中使用什么

change_table :addresses do |t|
  t.references :addressable, :polymorphic => true
end

Answer 1

其实,

   change_table :addresses do |t|
     t.remove_references :addressable
   end

会有点笨拙,不是吗？

编辑:正如Eben Geer指出的那样

   change_table :addresses do |t|
     t.remove_references :addressable, :polymorphic => true
   end

是这样做的正确方法.干杯!

Answer 2

def self.down
  change_table :addresses do |t|
    t.remove_references :addressable, :polymorphic => true
  end
end

Answer 3

class RemoveAddressableFromAddresses < ActiveRecord::Migration
  def change
    remove_reference :addresses, :addressable, polymorphic: true, index: true
  end
end

Answer 4

有什么问题？

def self.down
  remove_column :addresses, :addressable_type
  remove_column :addresses, :addressable_id
end