NoiseError in Devise :: SessionsController＃create undefined method`current_sign_in_at'

Question

[尝试在Rails应用中登录时出现以下错误。我使用devise进行身份验证。我的错误是Devise :: SessionsController＃create中的NoMethodError未定义的方法“ current_sign_in_at”

我的用户模型是

models/user.rb
 devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable, :omniauthable
attr_accessible :admin,:first_name, :last_name, :profile_name, :college_name, :email, :password, :password_confirmation, :remember_me, :provider, :uid
def admin?

end
def self.find_for_facebook_oauth(auth)
where(auth.slice(:provider, :uid)).first_or_initialize.tap do |user|
user.provider = auth.provider
user.uid = auth.uid
user.email = auth.info.email
user.password = Devise.friendly_token[0,20]
#user.name = auth.info.name   # assuming the user model has a name
#user.image = auth.info.image # assuming the user model has an image
user.save!
end
end
end

我的模式是

db/schema.rb
ActiveRecord::Schema.define(:version => 20140126101946) do

create_table "levels", :force => true do |t|
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end

create_table "users", :force => true do |t|
t.string   "first_name"
t.string   "last_name"
t.string   "profile_name"
t.string   "college_name"
t.string   "email",                  :default => "",    :null => false
t.string   "encrypted_password",     :default => "",    :null => false
t.string   "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.datetime "created_at",                                :null => false
t.datetime "updated_at",                                :null => false
t.string   "provider"
t.string   "uid"
t.boolean  "admin",                  :default => false
end

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

end

我的devise_create_users.rb中的代码是

class DeviseCreateUsers < ActiveRecord::Migration
def change
create_table(:users) do |t|
  t.string :first_name
  t.string :last_name
  t.string :profile_name
  t.string :college_name
  ## Database authenticatable
  t.string :email,              :null => false, :default => ""
  t.string :encrypted_password, :null => false, :default => ""

  ## Recoverable
  t.string   :reset_password_token
  t.datetime :reset_password_sent_at

  ## Rememberable
  t.datetime :remember_created_at

  ## Trackable
  t.integer  :sign_in_count, :default => 0
  t.datetime :current_sign_in_at
  t.datetime :last_sign_in_at
  t.string   :current_sign_in_ip
  t.string   :last_sign_in_ip

我的可追踪对象已被注释，我删除了注释，然后运行rake db：migrate，但没有任何反应。现在，我无法根据需要删除可跟踪的内容。我需要的是以某种方式可以保留我的设计，并以使其也添加到schema.rb的方式向其添加可跟踪的代码。

Answer 1

要向现有表中添加新列，仅更新已运行的迁移将不起作用，因为该模式的版本比现有迁移的版本高。如果您希望修改现有迁移，则可以使用以下命令运行down迁移：

rake db:migrate:down VERSION=20140126101944 # use version of the user migration

然后按照已完成的操作修改迁移并添加新列，然后使用以下命令运行up迁移：

rake db:migrate:up VERSION=20140126101944 # use version of the user migration

一种更好的方法是，如果您的应用程序已经在生产中，则使用更改添加新的迁移。

将trackable列添加到现有users表中：

class AddTrackableColumnsToUser < ActiveRecord::Migration
  def change
    change_table :users do |t|
      ## Trackable
      t.add_column :sign_in_count, :integer, :default => 0
      t.add_column :current_sign_in_at, :datetime
      t.add_column :last_sign_in_at, :datetime
      t.add_column :current_sign_in_ip, :string
      t.add_column :last_sign_in_ip, :string
    end
  end
end

然后运行db:migrate：

rake db:migrate