I have a ruby/rails/hobo system that someone wrote a couple years ago, that I need to port to the latest version of ruby/rails/hobo. It seems that ruby doesn't care about backward compatibility, so code that used to work in the old app doesn't work anymore: In the observation.rb model file, the old app has this: belongs_to :survey has_one :site, :through => :survey def create_permitted? acting_user == self.survey.contact or acting_user.administrator? end survey.rb model file has this: belongs_to :contact, :class_name => 'User', :creator => true Unfortunately the code in observation.rb doesn't work under the new ruby/rails/hobo, and it gives me the error: NoMethodError in Observations#index Showing controller: observations; dryml-tag: index-page where line #1 raised: undefined method `contact' for nil:NilClass Extracted source (around line #1): 0 Rails.root: /home/simon/ruby/frogwatch2 Application Trace | Framework Trace | Full Trace app/models/observation.rb:48:in `create_permitted?' How should the "create_permitted" method be changed? I'm finding that the documentation for ruby/rails/hobo is pretty atrocious (which is fair enough as it is free software). Also I don't even know how to begin searching for this on google (i've been trying for days). Please help! :)