element-ui树形表格展开与折叠

      <el-button
        icon="el-icon-s-fold"
        size="small"
        @click="toggleRowExpansion(true)"
        type="success"
        >展开</el-button
      >
      <el-button
        icon="el-icon-s-unfold"
        size="small"
        @click="toggleRowExpansion(false)"
        type="success"
        >折叠</el-button
      >
    //展开或者折叠树形结构
    toggleRowExpansion(isExpansion) {
      this.toggleRowExpansion_forAll(this.tableData, isExpansion);
    },
    toggleRowExpansion_forAll(data, isExpansion) {
      data.forEach((item) => {
        this.$refs.dataTreeList.toggleRowExpansion(item, isExpansion);
        if (item.children != undefined && item.children != null) {
          this.toggleRowExpansion_forAll(item.children, isExpansion);
        }
      });
    },