```ruby
class AddPreferencesToSpreePromotionAction < ActiveRecord::Migration
  def change
    unless column_exists? :preferences
      add_column :spree_promotion_actions, :preferences, :text
    end
  end
end
```

Fix checking column existence on migration
user
```ruby
class AddPreferencesToSpreePromotionAction < ActiveRecord::Migration
  def change
    unless column_exists?(:spree_promotion_actions, :preferences)
      add_column :spree_promotion_actions, :preferences, :text
    end
  end
end
```
assistant