element-ui 表格树形数据 的展示和收起

<template>
      //row-key 和ref 要必须写
 <el-table
  v-loading="load"
  element-loading-text="加载数据中"
  ref="theTable"
  :data="tableList"
  style="width: 100%"
  :row-key="add"
  :tree-props="{ children: 'children', hasChildren: 'hasChildren' }"
  :header-cell-style="{ background: '#eef1f6', color: '#606266' }"
  ></el-table>
  ......
</template>
method:{
     //筛选
    screenclick() {
      //点击筛选的时候 让筛选出来的数据展开
      this.forArr(this.tableList, false);
      this.getList();
    },
      // 重置
    Resetdata() {
      this.textval = "";
      //重置的时候 让数据全部收起
      this.forArr(this.tableList, false);
      this.getList();
    },
    //列表展开和收起
    forArr(arr, isExpand) {
      arr.forEach(i => {
        this.$refs.theTable.toggleRowExpansion(i, isExpand);
        if (i.children) {
          this.forArr(i.children, isExpand);
        }
      });
    },
}