无法找到管理员？在做Michael Hartl的教程时

Question

这是我的用户控制器，我正在做michael hartl的教程，但我在用户控制器中定义的current_user.admin?方法中遇到admin_user问题，而且我的destroy方法也有问题因为我也无法删除用户。

请问任何解决方案？

class UsersController < ApplicationController
  before_action :logged_in_user, only: [:index, :edit, :update, :destroy]
  before_action :correct_user, only: [:edit, :update]
  before_action :admin_user, only: :destroy

 def index
   @users = User.paginate(page: params[:page])
 end

  def new
    @user = User.new
  end

  def show
  @user = User.find(params[:id])
  end

  def create
  @user = User.new(user_params)
  if @user.save
    flash[:success] = 'Welcome to the Sample App!'
  redirect_to @user
  else
    render 'new'
  end
  end

  def edit
    @user = User.find(params[:id])
  end


  def update
    @user = User.find(params[:id])
    if @user.update_attributes(user_params)
    flash[:success] = 'Profile Updated'
      redirect_to @user
    else
      render 'edit'
    end
  end

  def destroy
    User.find(params[:id]).destroy
    flash[:success] = 'User deleted'
    redirect_to users_url
  end


  private
  def user_params
  params.require(:user).permit(:name, :email, :password,
                           :password_confirmation)
  end

  def logged_in_user
    unless logged_in?
      store_location
      flash[:danger] = 'Please log in.'
      redirect_to login_url
    end
  end

  def correct_user
    @user = User.find(params[:id])
    redirect_to(root_url) unless current_user?(@user)
  end

  def admin_user
    redirect_to(root_url) unless current_user.admin?
  end
end

User.rb

class User < ActiveRecord::Base
  attr_accessor :remember_token
  before_save { self.email = email.downcase }
  validates :name, presence: true, length: { maximum: 50 }
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :email, presence: true, length: { maximum: 255 },
        format: { with: VALID_EMAIL_REGEX },
        uniqueness: true
  has_secure_password
  validates :password, length: { minimum: 6 }

  def User.digest(string)
    cost = ActiveModel::SecurePassword.min_cost ? BCrypt::Engine::MIN_COST :
        BCrypt::Engine.cost
    BCrypt::Password.create(string, cost: cost)
  end

  def User.new_token
    SecureRandom.urlsafe_base64
  end

  def remember
    self.remember_token = User.new_token
    update_attribute(:remember_digest, User.digest(remember_token))
  end

  def authenticated?(remember_token)
    return false if remember_digest.nil?
    BCrypt::Password.new(remember_digest).is_password?(remember_token)
  end

  def forget
    update_attribute(:remember_digest, nil)
  end
end

删除

的链接

<li>
      <%= gravatar_for user %>
      <%= link_to user.name, user %>
      <% if current_user.admin? && !current_user?(user) %>
          | <%= link_to 'delete', user, method: :delete,
                    data: { confirm: 'You sure?' } %>
      <% end %>
    </li>