vue中解决v-for使用报红并出现警告

(Emitted value instead of an instance of Error) <Option v-for="item in searchTypeList">: component lists rendered with v-for should have explicit keys. See https://vuejs.org/guide/list.html#key for more info.

<ul

class="clearfix course-list">

<li

class="left"

v-for="(item,index)

in gradeClassfy.primary.grade"

:key="index"><a

href="#" rel="external nofollow" >{{item.name}}</a></li>

</ul>