Rails3中刪除我HABTM記錄時回調返回false

Question

我有這種模式：

class User < ActiveRecord::Base 
    has_and_belongs_to_many :roles 

    before_destroy do |u| 
    if u.superadmin? and User.joins(:roles).where(:roles => {:superadmin => true}).count == 1 
     u.errors.add(:base, "cannot delete last admin user") 
     return false 
    end 
    return true 
    end 
end 

class Role < ActiveRecord::Base 
    has_and_belongs_to_many :users 
end 

當我嘗試刪除最後一個超級管理員，在before_destroy回調增加錯誤排列並返回false。我在控制器中看到錯誤信息，一切似乎都沒有問題。

不包括 Rails3 從連接表中刪除了我的記錄。 爲什麼？我返回false，因爲我返回false它應該不繼續與刪除。這裏是日誌：

SQL (0.2ms) SELECT COUNT(*) FROM "users" INNER JOIN "roles_users" ON "roles_users"."user_id" = "users"."id" INNER JOIN "roles" ON "roles"."id" = "roles_users"."role_id" WHERE "roles"."superadmin" = 't' 
AREL (0.4ms) DELETE FROM "roles_users" WHERE "roles_users"."user_id" = 1 AND "roles_users"."role_id" IN (1, 4) 
Organization Load (0.4ms) SELECT * FROM "organizations" INNER JOIN "organizations_users" ON "organizations".id = "organizations_users".organization_id WHERE ("organizations_users".user_id = 1) 

感謝您的幫助。

Answer 1

這似乎是這個軌道誤差，如果使用較舊版本的Rails（它應該在的Rails 3.0.6 AFAIK來解決）：

https://rails.lighthouseapp.com/projects/8994/tickets/6191-habtm-association-is-being-destroyed-before-the-before_destory-callbacks-are-executed