Rake Migration：如何为所有用户输入auth_token到迁移中

Question

I recently added a new column called auth_token to my users which is suppose to be generated when the new user is created.

How do I add an auth_token to my existing users via migrations?
Source: http://railscasts.com/episodes/274-remember-me-reset-password

ps. I cannot find this in http://guides.rubyonrails.org/migrations.html so please don't send me there.

Answer 1

class DoThisThing < ActiveRecord:: Migration
   def self.up
      @users = Users.all
      @users.each do |user|
         user.auth_token = generate_token
         user.save
      end
   end
   def self.down
      puts "non recoverable migration"
   end
   def generate_token
      123456789
   end
end

You can put any standard Ruby/Rails code you like into a migration. Just be mindful of stdin/out and whether or not any particular libs you'd need are loaded into the memory space of the migration.