Element实现表格嵌套、多个表格共用一个表头的方法

<template>
 <div class="layout">
  <el-table :data="res" >
  <el-table-column prop="name">
   <template slot-scope="scope">
   <div class="tab_header">
    <span style="font-weight:600;">{{scope.row.name}}</span>
    <div class="operate">
    <span @click="handleEdit(scope.$index, scope.row)">修改</span>
    <span @click="handleDelete(scope.$index, scope.row)">删除</span>
    </div>
   </div>

   <!-- 这里要实现 多个表格共用一个表头，故需做判断，当表格要渲染的数据为default这个数组的时候，才显示表头的label值 -->
   <!-- 注意：当label无值的时候，还是会占用空间，故当前表格在页面上会出现一个代表表头的空行，需要手动更改（重写）Element表格的 thead样式 -->

   <div v-for="item in (scope.row.ext)" :key="item.id">
    <el-table :data="item" border :class="item!==scope.row.ext.default?'tab-thead-style':''" style="box-sizing: border-box;border-top:none;" :span-method="objectSpanMethod">
    <el-table-column :label="item===scope.row.ext.default?'运送到':''" prop="area"></el-table-column>
    <el-table-column :label="item===scope.row.ext.default?'首重':''" prop="weight"></el-table-column>
    <el-table-column :label="item===scope.row.ext.default?'运费':''" prop="first_price"></el-table-column>
    <el-table-column :label="item===scope.row.ext.default?'续重':''" prop="weight_incre"></el-table-column>
    <el-table-column :label="item===scope.row.ext.default?'最终运费':''" prop="extend_price"></el-table-column>
    </el-table>
   </div>

   </template>
  </el-table-column>
  </el-table>
 </div>
</template>
<script>
export default {
 data () {
 return {
  // res 参考的是后端返回的数据格式，
  res: [
  {
   id: 1,
   dealer_id: 0,
   name: '成都运费模板',
   type: 1,
   ext: {
   default: [{ area: '默认', type: 1, region: '1', weight: '首重d', weight_incre: '续重d', first_price: '运费d', extend_price: '最终运费d' }],
   free: [{ area: 'free', type: 1, region: '1', weight: '首重f', weight_incre: '续重f', first_price: '运费f', extend_price: '最终运费f' }, { area: 'free', type: 1, region: '1', weight: '首重f', weight_incre: '续重f', first_price: '运费f', extend_price: '最终运费f' }],
   pay: [{ area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }]
   }
  },
  {
   id: 2,
   dealer_id: 0,
   name: '重庆运费模板',
   type: 2,
   ext: {
   default: [{ area: '默认1', type: 1, region: '1', weight: '首重d', weight_incre: '续重d', first_price: '运费d', extend_price: '最终运费d' }],
   free: [{ area: 'free1', type: 1, region: '1', weight: '首重f', weight_incre: '续重f', first_price: '运费f', extend_price: '最终运费f' }, { area: 'free', type: 1, region: '1', weight: '首重f', weight_incre: '续重f', first_price: '运费f', extend_price: '最终运费f' }],
   pay: [{ area: 'pay1', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay1', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }, { area: 'pay', type: 1, region: '1', weight: '首重p', weight_incre: '续重p', first_price: '运费p', extend_price: '最终运费p' }]
   }
  }

  ]
 }
 },
 methods: {
 handleEdit (index, row) {
  console.log(index, row)
 },
 handleDelete (index, row) {
  console.log(index, row)
 },
 objectSpanMethod ({ row, column, rowIndex, columnIndex }) {
  if (columnIndex === 0) {
  if (rowIndex === 0) {
   let maxLen
   this.res.forEach(val => {
   const arr = [val.ext.default.length, val.ext.free.length, val.ext.pay.length]
   arr.sort((a, b) => a - b)// arr数组 按数字大小从小到大排序
   maxLen = arr.pop()// 取出排序后的数组arr中的最后一个元素
   })
   return {
   // 这个rowspan应该据 ext的default,pay,free的长度不同来定，取最大长度
   rowspan: maxLen,
   colspan: 1
   }
  } else {
   return {
   rowspan: 0,
   colspan: 0
   }
  }
  }
 }
 }
}
</script>
<style lang="scss">
.layout{

 .tab_header{
 color:#333;
 padding:0 5px 0 5px;
 height:45px;
 line-height:45px;
 border:1px solid #eee;display:flex;
 justify-content: space-between;
 background:rgb(233, 225, 225);
 }
 .operate{
 span{
  font-size: 14px;
  margin-right: 20px;
  margin-right:20px;
  color:#409EFF;
  cursor: pointer;
 }
 }
 /* 处理多个表格共用一个表头时，表头处出现多余空行的问题 （label置空后还是占据空间问题） */
 .tab-thead-style{
  thead{
   display: none;
  }
 }

}
</style>