无法读取未定义的属性错误：Vue绑定对象属性的类绑定类型错误
<p>我正在尝试根据对象属性绑定一个类，但是当我点击列表对象触发 @click 时，控制台告诉我无法读取 isSelected 的对象属性... 我正在尝试在动态渲染的列表项上使用一个函数来接收项目的 id，并将此属性设置为 false 或 true 时触发一个类来激活</p>
<p>希望有人能告诉我下面的代码中我漏掉了什么，谢谢 :)</p>
<pre class="brush:php;toolbar:false;"><ul class="daysList">
<li v-for="day in January" v-bind:class="{addedToTrip: day.isSelected}" class="daynum" @click="toggleIsSelected(day)" :key="day.id">
{{day.val}}
</li>
</ul></pre>
<p>我的 vue 数据</p>
<pre class="brush:php;toolbar:false;">data:function(){
return{
year: 2021,
month: 1,
day: 1,
days:[18,19,20,21],
January:[
{name: 'January', isSelected: false, id: 1, val:1},
{name: 'January', isSelected: false, id: 2, val:2},
{name: 'January', isSelected: false, id: 3, val:3},
{name: 'January', isSelected: false, id: 4, val:4},
{name: 'January', isSelected: false, id: 5, val:5},
{name: 'January', isSelected: false, id: 6, val:6},
{name: 'January', isSelected: false, id: 7, val:7},
{name: 'January', isSelected: false, id: 8, val:8},
{name: 'January', isSelected: false, id: 9, val:9},
{name: 'January', isSelected: false, id: 10, val:10},
{name: 'January', isSelected: false, id: 11, val:11},
{name: 'January', isSelected: false, id: 12, val:12},
{name: 'January', isSelected: false, id: 13, val:13},
{name: 'January', isSelected: false, id: 14, val:14},
{name: 'January', isSelected: false, id: 15, val:15},
{name: 'January', isSelected: false, id: 16, val:16},
{name: 'January', isSelected: false, id: 17, val:17},
{name: 'January', isSelected: false, id: 18, val:18},
{name: 'January', isSelected: false, id: 19, val:19},
{name: 'January', isSelected: false, id: 20, val:20},
{name: 'January', isSelected: false, id: 21, val:21},
{name: 'January', isSelected: false, id: 22, val:22},
{name: 'January', isSelected: false, id: 23, val:23},
{name: 'January', isSelected: false, id: 24, val:24},
{name: 'January', isSelected: false, id: 25, val:25},
{name: 'January', isSelected: false, id: 26, val:26},
{name: 'January', isSelected: false, id: 27, val:27},
{name: 'January', isSelected: false, id: 28, val:28},
{name: 'January', isSelected: false, id: 29, val:29},
{name: '一月', isSelected: false, id: 30, val:30},
{name: '一月', isSelected: false, id: 31, val:31},
],
二月：[]，
行进：[]，
四月：[]，
可能：[]，
六月：[]，
七月：[]，
八月：[]，
九月：[]，
十月：[]，
十一月：[]，
十二月：[]，
}
},</pre>
<p>评价 isSelected == true 时的 css 类</p>
.addedToTrip{
背景颜色：#2E9CFE；
顶部边框：.5px 纯黑色；
底部边框：.5px 纯黑色；
}</pre></p>