The problem of not displaying echarth embedded in the pop-up window of VUE element

Just click on an icon on the page, and a drawer-like pop-up window will pop up (the pop-up window is the drawer of element UI). Inside the pop-up window is the data presented by echarts. When I use echarts directly, the error dom is not obtained;

This is confused. I usually get it like this. Why doesn’t it work today. After searching for a lot of answers, I learned that the drawer was closed when I first entered the page. Then echarts does not get the dom. When I click the drawer, it comes out. At that time, there is an opened event, in which echarts is initialized and data is executed;

<el-drawer
      title="分析图表"
      :modal="false"
      :close-on-click-modal="false"
      :modal-append-to-body="false"
      size="600px"
      :visible.sync="dataVisible"
      @opened="opens"
    >
    <div ref="main" style="width: 100%;height:100%;"></div>
</el-drawer>

export default {
  data() {
    return {
      isColor: true,
      option1: {
        title: {
          text: '总资产占比分析',
          x: 'left'
        },
        tooltip: {
          trigger: 'item',
          formatter: '{a} <br/>{b} : {c} ({d}%)'
        },
        legend: {
          orient: 'vertical',
          right: '10%',
          top: '35%',
          data: ['A', 'B', 'C', 'D']
        },
        series: [
          {
            name: '访问来源',
            type: 'pie',
            radius: '70%',
            center: ['25%', '60%'],
            data: [
              { value: 335, name: 'A' },
              { value: 310, name: 'B' },
              { value: 234, name: 'C' },
              { value: 135, name: 'D' }
            ],
            label: {
              normal: {
                show: false,
                position: 'center'
              }
            }
          }
        ]
      },
}}
}
method:{
    opens(){
         this.$nextTick(() => {
            this.pie1()
      })
    },
    pie1(){
       this.$echarts.init(this.$refs.main).setOption(this.option1)
    }
}

Reprinted: In vue, the problem between the pop-up window using element ui and echarts