我已經改變了我的模型從我怎麼遷移DataMapper的AppEngine上
class Place
include DataMapper::Resource
has n, :trails
property :id, Serial
property :name, String, :length => 140
property :tag, String, :required => true
timestamps :at
end
到
class Place
include DataMapper::Resource
has n, :trails
property :id, Serial
property :name, String, :length => 140
property :tag, String, :required => true
property :trail_count, Integer, :default => 0
timestamps :at
end
我只是說 「屬性:trail_count,整型:默認=> 0」
並且我想遷移現有的appengine表,讓我有更多的字段「trail_count」 我讀過DataMapper.auto_upgrade!應該這樣做。
但我得到一個錯誤「未定義的方法`auto_upgrade!'對於DataMapper:模塊「
你能請幫助我如何遷移DM模型?