Rails 迁移——暂时忽略外键约束？

Question

我正在尝试将表的id字段更改为uuid

这是我的代码：

class AddUuidToProjects < ActiveRecord::Migration[5.0]
  def up
    add_column :projects, :uuid, :string, limit:36, null: false, first: true
    add_column :projects, :old_id, :integer

    Project.all.each do |p|
      p.update!(old_id: p.id)
    end
    change_table :projects do |t|
      t.remove :id
      t.rename :uuid, :id
    end
    execute "ALTER TABLE projects ADD PRIMARY KEY (id);"

    Project.all.each do |p|
      # has_one image
      Image.find(p.old_id).update!(project: p) 
      # has_many stories
      Story.where(project_id: p.old_id).each do |s|
        s.update!(project: p)
      end
    end
  end
  ...
end

t.remove :id由于外键约束，此迁移在尝试时中断。错误信息是：

Mysql2::Error: Cannot drop column 'id': needed in a foreign key constraint 'fk_rails_be41fd4bb7' of table 'db_dev.stories': ALTER TABLE `projects` DROP `id`

问题是，如果整个迁移运行，那么我将将该id列替换为另一列，并修复外键。那么，有没有办法可以忽略迁移的限制呢？

Answer 1

Project.connection.disable_referential_integrity do
  Project.delete_all # An example
end

ActiveRecord::Base.connection.disable_referential_integrity。

轨道 4.2+。