I have an after_save callback when I save an Organisation record. def after_save #create an admin user for this organisation if self.users.size.zero? user=User.new(:organisation_id=>self.id, :first_name => "Admin", :last_name => "User", :logon_name => "admin", :password => "secret_password", :privilege_bits => 3, :active => 1 ) user.save end end The User table has "validate_uniqueness_of" which appears to create a problem. class User < BaseServiceTable before_validation_on_create :set_initial_password serialize :permitted_programmes , Array attr_accessor :password_confirmation validates_presence_of :logon_name validates_uniqueness_of :logon_name, :scope => :organisation_id ........... Here is the sql from te dev log: SQL (0.1ms) BEGIN Organisation Exists (0.3ms) SELECT `organisations`.id FROM `organisations` WHERE (`organisations`.`logon_name` = BINARY ''abcd'') LIMIT 1 Organisation Create (0.3ms) INSERT INTO `organisations` (`name`, `logon_name`, `password`, `active`) VALUES(''ABcd Org'', ''abcd'', ''OrgPassword'', 1) SQL (0.4ms) SELECT count(*) AS count_all FROM `users` WHERE (`users`.organisation_id = 12) SQL (53.2ms) ROLLBACK Here is (top of) the stack trace: NoMethodError (You have a nil object when you didn''t expect it! The error occurred while evaluating nil.columns_hash): /usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/ validations.rb:723:in `validates_uniqueness_of'' /usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/ validations.rb:400 /usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/ validations.rb:397:in `each'' /usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/ validations.rb:397 I have had a look at the validation code and not sure what the problem is. Not sure if it is because User inherits from an abstract table? I am tempted just to do the validation manually as I dont have time for lengthy messing around, but I just wondered if anyone had seen the same problem? Cheers George -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.