迁移不回滚

Question

我有运行这个迁移：

class AddUniqueToLocationColumnName < ActiveRecord::Migration
  def change
    remove_index :locations, :name
    add_index :locations, :name, unique: true
  end
end

现在我正在尝试回滚，但它显示错误：

StandardError: An error has occurred, this and all later migrations canceled: remove_index is only reversible if given a :column option.

如何将此迁移回滚到我以前的版本？

Answer 1

尝试明确定义上下：

class AddUniqueToLocationColumnName < ActiveRecord::Migration
  def self.up
    remove_index :locations, column: :name
    add_index :locations, :name, unique: true
  end

  def self.down
    remove_index :locations, column: :name # remove unique index
    add_index :locations, :name # adds just index, without unique
  end
end

迁移不回滚

migration not rolling back

ruby-on-rails

rollback

rails-migrations