Rails 3 Tutorial 10.4.2 : NoMethodError undefined method `admin?' for nil:NilClass

i am doing and using for building my own authentication system, the Michael Hartls Tutorial for Rails 3 and came to an issue while doing it. I completed the whole section of 10.4.2 but when i got to the end and ran the test i always get this one error.

 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/controll开发者_如何学编程ers/users_controller.rb:68:in `admin_user'
     # ./spec/controllers/users_controller_spec.rb:245:in `block (5 levels) in <top (required)>'

I think it has something to do with my users controller in the admin area:

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

What is the problem and how do i fix this?

---

seems like you dont have a current user by the time you call 'destroy' method,

I think its because of this line

before_filter :admin_user,   :only => :destroy

and as you can see, you are setting current_user only in :index,:show,:edit, :update

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

Solution

adding :destroy to :authenticate method should fix the issue, and then by the time you try to destroy the current_user is there

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

---

Your current_user variable in the admin_user method is nil in that situation, so you need to check that the object isn't nil first:

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