urls are now unique, and a user can not add a friend with the exact same url

app/models/person.rb

@@ -6,7 +6,7 @@ class Person
   xml_accessor :url
  
   key :email, String
-  key :url, String, :unique => true
+  key :url, String
   
   one :profile, :class_name => 'Profile', :foreign_key => :person_id
   many :posts, :class_name => 'Post', :foreign_key => :person_id
@@ -16,15 +16,26 @@ class Person
   validates_presence_of :url
   validates_format_of :url, :with =>
      /^(https?):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*(\.[a-z]{2,5})?(:[0-9]{1,5})?(\/.*)?$/ix
-  validates_presence_of :email
+  
+     
+  validates_true_for :url, :logic => lambda { self.url_unique?}
 
+
+  validates_presence_of :email
+  
   before_validation :clean_url
  
   def real_name
     self.profile.first_name + " " + self.profile.last_name
   end
 
+  
   protected
+  
+  def url_unique?
+    same_url = Person.first(:url => self.url)
+    return same_url.nil? || same_url.id == self.id
+  end
 
   def clean_url
     self.url ||= "http://localhost:3000/" if self.class == User

spec/models/person_spec.rb

@@ -1,4 +1,10 @@
 require 'spec_helper'
 
 describe Person do
+  it 'should not allow a friend with the same url as the user' do
+    user = Factory.create(:user)
+    friend = Factory.build(:friend, :url => user.url)
+    friend.valid?.should == false
+
+  end
 end