ruby-on-rails - 添加 :on_delete to already existing foreign_key in rails migration

Question

我已经通过这种方式在数据库中创建了外键:

class CreateUser < ActiveRecord::Migration
  def change
    create_table do ... end
    add_foreign_key :users, :admins, column: :admin_id
  end
end

但忘记添加 on_delete: :nullify。迁移已被推送并用于生产。我想添加新的迁移，这将为此 PK 约束添加级联删除。如何实现？

Answer 1

您可以在下次迁移时删除和添加外键:

class ChangeForgeinKeyOnUsersTable < ActiveRecord::Migration[5.0]
  def change
    remove_foreign_key :users, column: :admin_id
    add_foreign_key :users, :admins, column: :admin_id, on_delete: :nullify
  end
end