class Comment < ActiveRecord::Base belongs_to :page belongs_to :author validate :safe_url def name if self.author self.author.name else self.user end end private def safe_url return true if self.url.to_s.empty? if self.url =~ /^http:\/\// and self.url !~ /[^a-zA-Z0-9\._:\-\/]/ true else self.errors.add(:url, "is not a permissible address") false end end end