用户#index中的NoMethodError

我有以下应用程序的问题，我一直在做railsCasts的Rails 3中的第211集Validages，但是当我尝试添加类EmailFormatValidator时会触发错误

NoMethodError in Users#index

Showing /home/fernando/Validations/store/app/views/users/index.html.erb where line #12 raised:

undefined method `each' for nil:NilClass
Extracted source (around line #12):

9:     <th></th>
10:   </tr>
11: 
12: <% @users.each do |user| %>
13:   <tr>
14:     <td><%= user.name %></td>
15:     <td><%= user.email %></td>
Rails.root: /home/fernando/Validations/store

车型/ user.rb

class User < ActiveRecord::Base
  validates :email, :presence => true, :uniqueness => true, :email_format => true
end

LIB / email_format_validator.rb

class EmailFormatValidator < ActiveModel::EachValidator
  def validate_each(object, attribute, value)
    unless value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
      object.errors[attribute] << (options[:message] || "is not formatted properly") 
    end
  end
end

/controller/user.rb

class UsersController < ApplicationController
  # GET /users
  # GET /users.json
  def index
    @users = User.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @users }
    end
  end

  # GET /users/1
  # GET /users/1.json
  def show
    @user = User.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @user }
    end
  end

#GET / users / new #GET /users/new.json def new @user = User.new

respond_to do |format|
  format.html # new.html.erb
  format.json { render json: @user }
end

结束

#GET / users / 1 /编辑def编辑@user = User.find（params [：id]）结束

#POST / users＃POST /users.json def create @user = User.new（params [：user]）

respond_to do |format|
  if @user.save
    format.html { redirect_to @user, notice: 'User was successfully created.' }
    format.json { render json: @user, status: :created, location: @user }
  else
    format.html { render action: "new" }
    format.json { render json: @user.errors, status: :unprocessable_entity }
  end
end

结束

#PUT / users / 1＃PUT /users/1.json def update @user = User.find（params [：id]）

respond_to do |format|
  if @user.update_attributes(params[:user])
    format.html { redirect_to @user, notice: 'User was successfully updated.' }
    format.json { head :no_content }
  else
    format.html { render action: "edit" }
    format.json { render json: @user.errors, status: :unprocessable_entity }
  end
end

结束

#DELETE / users / 1＃DELETE /users/1.json def destroy @user = User.find（params [：id]）@ user.destroy

respond_to do |format|
  format.html { redirect_to users_url }
  format.json { head :no_content }
end

结束

当我在UsersController #index中单击一次ArgumentError时，会出现此错误

Unknown validator: 'EmailFormatValidator'
Rails.root: /home/fernando/Validations/store