我有个city表和一个shop表，我想验证在同一个城市下shop表的name不能重复，怎么办呢？
[b]问题补充：[/b]
有办法在model里边验证么？
validates_uniqueness_of :name,:scope => "city_id"
shops = Shop.find :all , :conditions => ["city_id=? and name=?",params[:city_id],params[:name]]
if shop.blank?
无重名
else
有重名
end