A default exposure for decent_exposure that assigns instance variables (to make cancan happy)

cancan_exposure.rb

default_exposure do |name|
  collection = name.to_s.pluralize
  if respond_to?(collection) && collection != name.to_s && send(collection).respond_to?(:scoped)
    proxy = send(collection)
  else
    proxy = name.to_s.classify.constantize
  end

  instance_variable_set("@#{name}") = if id = params["#{name}_id"] || params[:id]
    proxy.find(id).tap do |r|
      r.attributes = params[name] unless request.get?
    end
  else
    proxy.new(params[name])
  end
end