Ruby on Rails - Acts_as_taggable_on迁移失败

Question

我正在使用 Rails 3.0.6/Ruby 1.8.7，我一直在尝试让 acts_as_taggable_on （2.0.6） gem 工作，但它似乎在默认迁移中失败了。日志：

==  ActsAsTaggableOnMigration: migrating ======================================
-- create_table(:tags)
   -> 0.3175s
-- create_table(:taggings)
rake aborted!
An error has occurred, all later migrations canceled:
Mysql2::Error: Can't create table 'project_development.taggings' (errno: 150): 
CREATE TABLE `taggings` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY, 
`tag_id` int(11), `taggable_id` int(11), `taggable_type` varchar(255), `tagger_id` 
int(11), `tagger_type` varchar(255), `context` varchar(255), `created_at` datetime, 
FOREIGN KEY (`tag_id`) REFERENCES `tags` (`id`), FOREIGN KEY (`taggable_id`) REFERENCES 
`taggables` (`id`), FOREIGN KEY (`tagger_id`) REFERENCES `taggers`    (`id`)) ENGINE=InnoDB

因此，看起来:p olymorphic => true属性无法按预期工作。谷歌似乎不是很有帮助（报告了类似的错误，例如 http://www.ruby-forum.com/topic/194219）。有什么方法可以解决吗？宝石替代品？

解决automatic_foreign_key与这颗宝石冲突

Answer 1

是否修改了迁移以添加外键约束？

在 2.0.6 上的行为可标记中提供的迁移如下所示：

class ActsAsTaggableOnMigration < ActiveRecord::Migration
      def self.up
        create_table :tags do |t|
          t.column :name, :string
        end
        create_table :taggings do |t|
          t.column :tag_id, :integer
          t.column :taggable_id, :integer
          t.column :tagger_id, :integer
          t.column :tagger_type, :string
          # You should make sure that the column created is
          # long enough to store the required class names.
          t.column :taggable_type, :string
          t.column :context, :string
          t.column :created_at, :datetime
        end
        add_index :taggings, :tag_id
        add_index :taggings, [:taggable_id, :taggable_type, :context]
      end
      def self.down
        drop_table :taggings
        drop_table :tags
      end
    end