解决vue 中 echart 在子组件中只显示一次的问题

// Main.vue
<template>
 <div>
  ...
  <Pie :pieData="fullList"></Pie>
  ...
 </div>
</template>
<script>
 import Pie from 'components/SourcePie'
 export default {
 components: {
 Pie
 },
 data(){
  return {
  fullList:{}
 }
 },
 mounted() {
 this._fullQuantity()
 },
 methods: {
 _fullQuantity(){
  // axios...
 }
 }
 }
</script>

// SourcePie.vue
<template>
 <div style="width:300px;height:260px" id="data_source_con" v-if="pieData"></div>
</template>
<script>
import echarts from 'echarts';
export default {
 name: 'dataSourcePie',
 data() {
 return {
  //
 };
 },
 props: {
 pieData: Object
 },
 mounted() {
 this.init()
 },
 methods: {
 init() {
  let _this = this;
  this.$nextTick(() => {
  var dataSourcePie = echarts.init(document.getElementById('data_source_con'));
  const option = {
   tooltip: {
   trigger: 'item',
   formatter: "{a} <br/>{b} : {c} ({d}%)",
   position: ['50%', '50%']
   },
   series: [{
   name: '实体统计',
   type: 'pie',
   radius: '50%',
   center: ['50%', '60%'],
   data: [{
    value: _this.pieData.videoNum,
    name: '影视数据'
    },
    {
    value: _this.pieData.albumNum,
    name: '专辑数据'
    },
    {
    value: _this.pieData.songNum,
    name: '歌曲数据'
    },
    {
    value: _this.pieData.novelNum,
    name: '小说数据'
    },
    {
    value: _this.pieData.presonNum,
    name: '人员数据'
    }
   ],
   itemStyle: {
    emphasis: {
    shadowBlur: 10,
    shadowOffsetX: 0,
    shadowColor: 'rgba(0, 0, 0, 0.5)'
    }
   }
   }]
  };
  dataSourcePie.setOption(option);
  window.addEventListener('resize', function() {
   dataSourcePie.resize();
  });
  });
 }
 }
};
</script>

watch: {
 pieData() {
  this.$nextTick(() => {
  if (this.pieData) {
   this.init()
  }
  })
 }
 },