接受具有多对多关联的展平值

Question

我想要一个模型User接受另一个模型的值，Contact :: Skill。我希望用户能够从用户编辑页面更新他们的Contact :: Skill属性。这两个模型与联接表contact_skills_users具有多对多关联。

它不会保存到表，contact_skills或联接表contact_skills_users。但是，看着日志，我找不到问题。

AREL (0.3ms)  INSERT INTO `contact_skills` (`name`, `created_at`, `updated_at`) VALUES ('joe user skills', '2011-08-15 18:06:30', '2011-08-15 18:06:30')
Contact::Skill Load (0.4ms)  SELECT `contact_skills`.* FROM `contact_skills` WHERE `contact_skills`.`id` = 12 LIMIT 1
Contact::Skill Load (0.5ms)  SELECT * FROM `contact_skills` INNER JOIN `contact_skills_users` ON `contact_skills`.id = `contact_skills_users`.skill_id WHERE (`contact_skills_users`.user_id = 3 )
SQL (0.2ms)  INSERT INTO `contact_skills_users` (`skill_id`, `user_id`) VALUES (12, 3)

我的用户模型中的代码：

has_and_belongs_to_many :skills,  :class_name => '::Contact::Skill',
                                  :join_table => 'contact_skills_users'
accepts_flattened_values_for :skills, :value => :name