filling in the user model

cookbook/015/hodgepodge/app/models/user.rb

@@ -1,2 +1,10 @@
 class User < ActiveRecord::Base
+  validates_uniquness_of :username
+  validates_confirmation_of :password, :on => :create
+  validates_length_of :password, :within => 5..40
+
+  def self.authenticate(user_info)
+    find_by_username_and_password(user_info[:username],
+                                  user_info[:password])
+  end
 end