1  #---
   2  # Excerpted from "Agile Web Development with Rails, 3rd Ed.",
   3  # published by The Pragmatic Bookshelf.
   4  # Copyrights apply to this code. It may not be used to create training material, 
   5  # courses, books, articles, and the like. Contact us if you are in doubt.
   6  # We make no guarantees that this code is fit for any purpose. 
   7  # Visit http://www.pragmaticprogrammer.com/titles/rails3 for more book information.
   8  #---
   9  require 'digest/sha1'
  10 
  11 
  12  class User < ActiveRecord::Base
  13    
  14    validates_presence_of     :name
  15    validates_uniqueness_of   :name
  16   
  17    attr_accessor :password_confirmation
  18    validates_confirmation_of :password
  19 
  20    validate :password_non_blank
  21    
  22 
  23    
  24    def self.authenticate(name, password)
  25      user = self.find_by_name(name)
  26      if user
  27        expected_password = encrypted_password(password, user.salt)
  28        if user.hashed_password != expected_password
  29          user = nil
  30        end
  31      end
  32      user
  33    end
  34    
  35    
  36    # 'password' is a virtual attribute
  37    
  38    def password
  39      @password
  40    end
  41    
  42    def password=(pwd)
  43      @password = pwd
  44      return if pwd.blank?
  45      create_new_salt
  46      self.hashed_password = User.encrypted_password(self.password, self.salt)
  47    end
  48    
  49    
  50 
  51    
  52    def after_destroy
  53      if User.count.zero?
  54        raise "Can't delete last user"
  55      end
  56    end     
  57    
  58 
  59  private
  60 
  61    def password_non_blank
  62      errors.add(:password, "Missing password") if hashed_password.blank?
  63    end
  64 
  65    
  66    
  67    def create_new_salt
  68      self.salt = self.object_id.to_s + rand.to_s
  69    end
  70    
  71    
  72    
  73    def self.encrypted_password(password, salt)
  74      string_to_hash = password + "wibble" + salt
  75      Digest::SHA1.hexdigest(string_to_hash)
  76    end
  77    
  78 
  79  end
  80