原文1
原文2
原文3

一、如果全部展开

default-expand-all="true"

二、设置有数据的行打开下拉

1、父table需要绑定两个属性expand-row-key和row-key

 <el-table
      :data="tableData"
      :expand-row-keys="expends"  //expends是数组，设置你要展开行的id
      :row-key="getRowKeys" //通过getRowKeys方法获取到row的行id值
      >

2、data中设置

 data() {
    return {
      expends:[],
      }
   }

3、methods中设置

 methods: {
    //设置table中的扩展项，展开的id，此处需要全部展开
    getExpends(){
      var Id = this.tableData.map(item => item.id)
            this.expends = Id
    },
    getRowKeys(row){
      return row.id
    },
    }

如果是有数据的展开：

4、created()中调用 getExpends()，使一打开网页就全部展开（注意你的父tableData数据得先拿到才调用getExpends方法）

created() {
    this.getExpends();
  },

三、对当前展开行内容修改，当前行默认展开

:row-key="getRowKeys"
<!--添加父表默认展开的数组以ID -->
:expand-row-keys="expandednewarr"
@expand-change="expandChange"

<el-table-column align="center" type="expand">
	<template slot-scope="props">
	<el-table
	:data="props.row.list"
	row-key="id"

	expandChange(row, expandedRows) {
      this.expandednewarr = expandedRows.map(item => item.id.toString());
    },

全部代码：

<template>
  <div class="mod-config">
    <el-form
      :inline="true"
      :model="dataForm"
      @keyup.enter.native="getDataList()"
    >
      <el-form-item>
        <el-button type="primary" @click="drawanjuan()">领取案卷</el-button>
      </el-form-item>
    </el-form>
    <el-table
      :data="dataList"
      v-loading="dataListLoading"
      style="width: 100%;"
      stripe
      :row-key="getRowKeys"
      :expand-row-keys="expandednewarr"
      @expand-change="expandChange"
      max-height="680"
    >
      <el-table-column align="center" type="expand">
        <template slot-scope="props">
          <el-table
            :data="props.row.list"
            style="width: 100%"
            class="child-table"
            row-key="id"
            stripe
          >
            <el-table-column width="60" align="center"></el-table-column>
            <el-table-column prop="id" label="ID" />
            <el-table-column prop="anjuanName" label="案卷名称" />
            <el-table-column prop="chaijuanStartTime" label="拆卷开始时间">
              <template slot-scope="{ row }">
                {{ row.chaijuanStartTime || "null" }}
              </template>
            </el-table-column>
            <el-table-column prop="chaijuanEndTime" label="拆卷结束时间">
              <template slot-scope="{ row }">
                {{ row.chaijuanEndTime || "null" }}
              </template>
            </el-table-column>
            <el-table-column label="操作">
              <template slot-scope="scope">
                <el-button
                  v-if="isAuth('ycl:chaijuanrecord:update')"
                  type="text"
                  size="small"
                  @click="chaijuanstatusbtn(scope.row)"
                >
                  {{ getButtonLabel(scope.row) }}
                </el-button>
              </template>
            </el-table-column>
          </el-table>
        </template>
      </el-table-column>
      <el-table-column label="ID" prop="id"></el-table-column>
      <el-table-column label="调卷姓名" prop="createName"></el-table-column>
      <el-table-column label="调卷数量" prop="numsection"></el-table-column>
      <el-table-column label="调卷前缀" prop="diaojuanPrefix"></el-table-column>
      <el-table-column label="调卷位置" prop="diaojuanPath"></el-table-column>
      <el-table-column label="调卷时间" prop="createTime"></el-table-column>
    </el-table>
    <el-pagination
      @size-change="sizeChangeHandle"
      @current-change="currentChangeHandle"
      :current-page="pageIndex"
      :page-sizes="[10, 20, 50, 100]"
      :page-size="pageSize"
      :total="totalPage"
      layout="total, sizes, prev, pager, next, jumper"
    >
    </el-pagination>
    <add-or-update
      v-if="addOrUpdateVisible"
      ref="addOrUpdate"
      @refreshDataList="getDataList"
    ></add-or-update>
  </div>
</template>
 
<script>
import AddOrUpdate from "./chaijuanrecord-add-or-update";
export default {
  data() {
    return {
      dataForm: {
        archivesCode: "",
        archivesName: "",
        username: ""
      },
      dataList: [],
      pageIndex: 1,
      pageSize: 10,
      totalPage: 0,
      dataListLoading: false,
      dataListSelections: [],
      addOrUpdateVisible: false,
      expandednewarr: [],
      getRowKeys(row) {
        return row.id;
      }
    };
  },
  components: {
    AddOrUpdate
  },
  activated() {
    this.getDataList();
  },
  methods: {
    // 获取数据列表
    getDataList() {
      this.dataListLoading = true;
      this.$http({
        url: this.$http.adornUrl("/chai-juan-record/pageList"),
        method: "get",
        params: this.$http.adornParams({
          page: this.pageIndex,
          limit: this.pageSize
        })
      }).then(({ data }) => {
        if (data && data.code === 0) {
          this.dataList = data.page.list;
          this.dataList.forEach(item => {
            item.numsection = item.startNumber + "-" + item.endNumber;
          });
          this.totalPage = data.page.totalCount;
        } else {
          this.dataList = [];
          this.totalPage = 0;
        }
        this.dataListLoading = false;
      });
    },
    // 每页数
    sizeChangeHandle(val) {
      this.pageSize = val;
      this.pageIndex = 1;
      this.getDataList();
    },
    // 当前页
    currentChangeHandle(val) {
      this.pageIndex = val;
      this.getDataList();
    },
    drawanjuan() {
      this.addOrUpdateVisible = true;
      this.$nextTick(() => {
        this.$refs.addOrUpdate.init();
      });
    },
    expandChange(row, expandedRows) {
      this.expandednewarr = expandedRows.map(item => item.id.toString());
    },
    chaijuanstatusbtn(row) {
      const data = {
        id: row.id
      };
      this.$http({
        url: this.$http.adornUrl("/chai-juan-record/startAnEndChaiJuan"),
        method: "post",
        data: data
      }).then(({ data }) => {
        if (data && data.code === 0) {
          this.getDataList();
        }
      });
    },
    getButtonLabel(row) {
      if (row.chaijuanStartTime === null) {
        return "开始拆卷";
      } else if (
        row.chaijuanStartTime !== null &&
        row.chaijuanEndTime === null
      ) {
        return "结束拆卷";
      } else {
        return "已完成拆卷";
      }
    }
  }
};
</script>
<style scoped lang="scss">
.mod-config {
  padding: 20px;
}
/deep/.el-table tbody tr:hover > td {
  background-color: transparent !important;
}
</style>