Property "rules" was accessed during render but is not defined on instance.

项目中经常出现警告Property "xxx" was accessed during render but is not defined on instance.说明xxx没有定义就在某个地方用了。xxx可以是属性也可以是方法。 表单用了验证规则，却还没有定义rules,在data中添加rules即可： 警告解决。