vant的picker的坑及解决

<view class="picker" bindtap="goSub">
	{{subjectname}}
	<image class="img" src="../../images/bottom-arrow-pic.png"></image>
	<!-- 年级筛选 -->
	<van-popup show="{{ subShow }}" bind:close="subClose" position="bottom" overlay-style="background:rgba(0,0,0,0.3)">
		<van-picker columns="{{ subColumns }}" bind:cancel="subCancel" bind:confirm="subConfirm" show-toolbar value-key="name"
		 toolbar-class="cancon" />
	</van-popup>
</view>

<view class="picker" bindtap="goSub">
    {{subjectname}}
    <image class="img" src="../../images/bottom-arrow-pic.png"></image>
</view>
<!-- 年级筛选 -->
<van-popup show="{{ subShow }}" bind:close="subClose" position="bottom" overlay-style="background:rgba(0,0,0,0.3)">
    <van-picker columns="{{ subColumns }}" bind:cancel="subCancel" bind:confirm="subConfirm" show-toolbar value-key="name"
     toolbar-class="cancon" />
</van-popup>

<div class="content">
    <div @click="openPicker()">{{pickerValue}}</div>
    <van-popover v-model="showPicker" position="bottom">
      <van-picker
        :columns="columns"
        show-toolbar
        :default-index="defaultIndex"
        @confirm="setData"
        @cancel="showPicker = false"
      ></van-picker>
    </van-popover>
  </div>

showPicker:false,
      defaultIndex:0,
      pickerValue0:'浙江',
      pickerValue:'温州',
      columns: [{
        text: '浙江',
        defaultIndex:NaN,
        children: [{
          text: '杭州',
          defaultIndex:NaN
        }, {
          text: '温州',
          defaultIndex:NaN
        }]
      }, {
        text: '福建',
        defaultIndex:NaN,
        children: [{
          text: '福州',
          defaultIndex:NaN
        }, {
          text: '厦门',
          defaultIndex:NaN
        }]
      }]

 openPicker(){
    //  打开筛选框的默认值
     this.columns.map((item,index)=>{
       if(this.pickerValue0===item.text){
         this.defaultIndex = parseInt(index)
         for(let i =0 ;i<item.children.length;i++){
           if(this.pickerValue === item.children[i].text){
             item.defaultIndex = parseInt(i)
           }
         }  
       }
     })
     console.log(this.columns);
     this.showPicker = true
   },