Rails 3教程10.4.2：NoMethodError未定義方法`admin？' 為零：NilClass

Question

我正在做和使用建立我自己的身份驗證系統， 邁克爾哈特爾Rails 3教程，並在這樣做時遇到了一個問題。 我完成了10.4.2的整個部分，但是當我到達最后並運行測試時，我總是得到這一個錯誤。

 1) UsersController GET 'index' DELETE 'destroy' as a non-signed-in user should deny access
     Failure/Error: delete :destroy, :id => @user
     NoMethodError:
       undefined method `admin?' for nil:NilClass
     # ./app/controllers/users_controller.rb:68:in `admin_user'
     # ./spec/controllers/users_controller_spec.rb:245:in `block (5 levels) in <top (required)>'

我認為它與管理區域中的用戶控制器有關：

class UsersController < ApplicationController
    before_filter :authenticate, :only => [:index,:show,:edit, :update]
    before_filter :correct_user, :only => [:edit, :update]
    before_filter :admin_user,   :only => :destroy
        .
        .
        .
        .
        .
    def destroy
        User.find(params[:id]).destroy
        flash[:success] = "USER DELETED."
        redirect_to users_path
    end


    private

        def authenticate
            deny_access unless signed_in?
        end

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

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

有什么問題，我該如何解決這個問題？

Answer 1

看起來你在調用'destroy'方法時沒有當前用戶，

我認為這是因為這條線

before_filter :admin_user,   :only => :destroy

如您所見，您只在以下位置設置current_user：index，：show，：edit，：update

before_filter :authenticate, :only => [:index,:show,:edit, :update]

解

添加：destroy to：authenticate方法應該修復問題，然后在你嘗試銷毀current_user的時候就到了

before_filter :authenticate, :only => [:index,:show,:edit, :update, :destroy]

Answer 2

在這種情況下， admin_user方法中的current_user變量為nil，因此您需要先檢查對象是否為nil：

def admin_user
  authenticate # if this method doesn't terminate the processing, you'll have to alter the line below too
  redirect_to(root_path) unless current_user.admin?
  # or: redirect_to(root_path) unless current_user && current_user.admin?
end