lib/active_record_survey/node/answer/rank.rb
def validate_instance_node(instance_node)
			# super - all validations on this node pass
			super &&
			(instance_node.value.to_s.empty? || !instance_node.value.to_s.match(/^\d+$/).nil?) &&
			(instance_node.value.to_s.empty? || instance_node.value.to_i >= 1) &&
			instance_node.value.to_i <= self.max_rank
		end
def validate_instance_node(instance_node)
			# super - all validations on this node pass
			super &&
			(instance_node.value.to_s.empty? || !instance_node.value.to_s.match(/^\d+$/).nil?) &&
			(instance_node.value.to_s.empty? || instance_node.value.to_i >= 1) &&
			instance_node.value.to_i <= self.max_rank
		end
Accept integer or empty values
 Must be within range of the number of ranking nodes