页面重定向后attr_accessor = nil？

Question

I am using Hartl's Tutorial for Account Activation

user.rb
attr_accessor :activation_token

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

# Returns a random token.
def User.new_token
  SecureRandom.urlsafe_base64
end

def send_activation_email
    UserMailer.account_activation(self).deliver_now
end

def create_activation_digest
  self.activation_token  = User.new_token
  self.activation_digest = User.digest(activation_token)
end

Once the update action shown below in my UsersController is complete and the user is redirected to the root_url

def update
  @user = User.find(params[:id])
    ...
    elsif !params[:user][:email].blank?
      if @user.authenticate(params[:user][:current_password])
        @user.update_attributes(email_user_params)
        if @user.save
          @user.create_activation_digest
          @user.deactivated
          @user.send_activation_email
          log_out
          flash[:info] = "Please check email dude"
          redirect_to root_url
        else
          flash[:danger] = "Email Update Failed"
          redirect_to edit_user_email_path(@user)
        end
     else
       flash[:danger] = "Current Password Is Incorrect"
       redirect_to edit_user_email_path(@user)
     end
   ...

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

then:

:activation_token = nil.

Is that correct?

I am asking because there are a bunch of topics on the subject of allowing the user to request a second validation email in a separate controller action and in all of those topics the discussion is stuck on routing issues, because in the email that is sent, the :activation_token is used as :id and the error message comes up :id -> nil

Edit:

class AccountActivationsController < ApplicationController

def edit
  user = User.find_by(email: params[:email])
    if user && !user.activated? && user.authenticated?(:activation, params[:id])
      user.activate
      log_in user
      flash[:success] = "Account activated!"
      redirect_to user
    else
      flash[:danger] = "Invalid activation link"
      redirect_to root_url
    end
  end
end

 user.rb
 def authenticated?(attribute, token)
    digest = send("#{attribute}_digest")
    return false if digest.nil?
    BCrypt::Password.new(digest).is_password?(token)
 end

Answer 1

So it appears that since you are using a virtual attribute to store that token at some point in time that object is leaving scope and being reloaded or some such even that is cause you to loose context. The best bet is just to ad a column to your User table to persist it between contexts and just update it where appropriate.

Answer 2

I also met this problem. Even though I removed "redirect_to root_url", after the code runs into a different action (in the same controller), the attr_accessor still becomes nil.

Thus my conclusion is that the lifetime of an attr_accessor only exists within the same action.