Fun recursive function to test if things like copying deep data structures work correctly. Done with @boconnell at @remix.

identity_of_model.rb

def identity_of_model(model, global_excluded=['id', 'created_at', 'updated_at', 'deleted_at'])
  excluded_columns = model.class.reflect_on_all_associations.map(&:foreign_key) + global_excluded
  identity = model.attributes.except(*excluded_columns)  
  model.class.reflect_on_all_associations(:has_many).sort_by(&:name).each do |ref|   
    identity[ref.name.to_s] = model.send(ref.name).map(&method(:identity_of_model)).sort_by(&:to_json)      
  end
  model.class.reflect_on_all_associations(:has_and_belongs_to_many).sort_by(&:name).each do |ref|
    identity["#{ref.name}_counts"] = model.send(ref.name).count
  end
  identity
end

identity_of_model(Map.first) == identity_of_model(copy(Map.first))