• 最近写需求时用到了expand-change表格展开回调，但我发现第一次展开后并没有展示任何数据，但我的返回值是存在的，当第二次展开时发现数据就有了。此原因是因为获取数据的接口是异步的，导致Dom渲染不同步导致的，其实解决办法也很简单，只需在外层的表格列表中的每一个数组对象加一个空数据作为默认展示即可

1 . 解决expand-change第一次展开无数据显示问题

• 首先：定义好需要展示的数据并设置type="expand"展开子表格，用expand-change来获取当前行展开回调，设置row-key防止数据混乱（这个要加上不然，展开行又自己合上了）

<template>
  <el-table :data="tableData" @expand-change="handleExpand" :border="parentBorder" style="width: 100%">
    <el-table-column type="expand">
      <template #default="props">
        <div m="4">
          <p m="t-0 b-2">State: {{ props.row.number || '' }}</p>
          <p m="t-0 b-2">City: {{ props.row.chargeTime || '' }}</p>
          <p m="t-0 b-2">Address: {{ props.row.serverAmount|| '' }}</p>
          <h3>Family</h3>
          <el-table :data="props.row.family" :border="childBorder">
            <el-table-column label="Name" prop="name" />
            <el-table-column label="State" prop="state" />
            <el-table-column label="City" prop="city" />
            <el-table-column label="Address" prop="address" />
            <el-table-column label="Zip" prop="zip" />
          </el-table>
        </div>
      </template>
    </el-table-column>
    <el-table-column label="Date" prop="date" />
    <el-table-column label="Name" prop="name" />
  </el-table>
</template>

<script lang="ts" setup>
import { ref } from 'vue'

const parentBorder = ref(false)
const childBorder = ref(false)
const tableData = [
  {
    date: '2016-05-03',
    name: 'Tom',
    state: 'California',
    city: 'San Francisco',
    address: '3650 21st St, San Francisco',
  },
  {
    date: '2016-05-02',
    name: 'Tom',
    state: 'California',
    city: 'San Francisco',
    address: '3650 21st St, San Francisco',
  },
  {
    date: '2016-05-04',
    name: 'Tom',
    state: 'California',
    city: 'San Francisco',
    address: '3650 21st St, San Francisco',
  },
]

// 展开某行详情
const handleExpand = async (item, expandedRows) => {
  if (!item.expand) {
    const detail = await api.front.remoteConfig.getBillDetail({ number: item.number })
    item.number = detail.number
    item.chargeTime = detail.chargeTime
    item.serverAmount = detail.serverAmount
    item.expand = true
  }
}
</script>