Ruby on rails 3 在自己的标记实现后执行ActsAsTaggableOn

我在rails应用程序中有自己的标记实现，并希望用ActsAsTaggableOn gem替换它。我生成了迁移并删除了所有带有标记的迁移，但是忘记了首先回滚，所以我只做了rake db:reset。现在，模式中有tag和taggable看起来不错，但是如果我在控制台中尝试使用tag，只需键入tag我就可以得到

NameError: uninitialized constant Tag

是什么导致了这个错误，我想我只是喜欢上了

My schema.rb如下所示：

# encoding: UTF-8
# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended to check this file into your version control system.

ActiveRecord::Schema.define(:version => 20121009203921) do

  create_table "comments", :force => true do |t|
    t.text     "content"
    t.integer  "user_id"
    t.integer  "message_id"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "events", :force => true do |t|
    t.string   "name"
    t.datetime "start_at"
    t.datetime "end_at"
    t.integer  "user_id"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "messages", :force => true do |t|
    t.text     "content"
    t.integer  "user_id"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "taggings", :force => true do |t|
    t.integer  "tag_id"
    t.integer  "taggable_id"
    t.string   "taggable_type"
    t.integer  "tagger_id"
    t.string   "tagger_type"
    t.string   "context",       :limit => 128
    t.datetime "created_at"
  end

  add_index "taggings", ["tag_id"], :name => "index_taggings_on_tag_id"
  add_index "taggings", ["taggable_id", "taggable_type", "context"], :name => "index_taggings_on_taggable_id_and_taggable_type_and_context"

  create_table "tags", :force => true do |t|
    t.string "name"
  end

  create_table "users", :force => true do |t|
    t.string   "name"
    t.string   "email"
    t.datetime "created_at",                            :null => false
    t.datetime "updated_at",                            :null => false
    t.string   "encrypted_password"
    t.string   "salt"
    t.boolean  "admin",              :default => false
    t.string   "phone"
    t.string   "street"
    t.string   "zip"
    t.string   "location"
  end

  add_index "users", ["email"], :name => "index_users_on_email", :unique => true

end

---

谢谢你的帮助

我必须有一个模型，才能在控制台中工作