效果图：

需求：配置优惠活动优惠券包，一个活动可以配置一张或者多张优惠券 

 数据支持：

{
                "id": 9, //活动id
                 ...,
                "coupon_pack": [
                    {
                        "id": 19, //券包的id
                        "coupon_id": 9,
                        ...
                    }，
                    {
                        "id": 20, //券包的id
                        "coupon_id": 9,
                        ...
                    }
                ],
 
            },

代码实现：

1.调用接扣获取数据 将二维数组降维成一维数组

//降维的方法
const showList = (list: any[]) => {
	const mergeList = ref<any[]>([]) //合并后的列表
	let newItem = {} as any
	list.forEach(item => {
		item.coupon_pack.map(pack => {
			pack.child_id = pack.id
			const { id, ...rest } = pack
			return rest
		}).forEach(pack => {
			newItem = {
				...item,
				...pack
			}
			mergeList.value.push(newItem)
		})
	})
	return mergeList.value
}
//从后端获取数据
const couponList = ref<ICouponListResponse[]>([])
const getCouponList = async () => {
	
	const res = await reqxxxxx(page.value, pageSize.value, params) //调用接口
	if (res.code !== 0) {
		
		return ElMessage.error(res.message)
	}
	total.value = res.data.total
	couponList.value = res.data.data
	couponList.value = await showList(couponList.value) //转换成一维数组
    getMergeRow(couponList.value) //合并前的准备
}

2. 获取需要合并的行和开始合并的位置，完成合并

const getMergeRow = (list: any[]) => {
	for (var i = 0; i < list.length; i++) {
		if (i === 0) {
			mergeRowCount.value.push(1) //第一个数据 默认合并1行
			mergePosition.value = 0 //开始位置下标默认为0
		} else {
			// 相同id进行合并
			if (list[i].id === list[i - 1].id) {
				mergeRowCount.value[mergePosition.value] += 1;
				mergeRowCount.value.push(0);
			} else {
				mergeRowCount.value.push(1);
				mergePosition.value = i;
			}
		}
	}
}
interface SpanMethodProps {
	row: ICouponListResponse
	column: TableColumnCtx<ICouponListResponse>
	rowIndex: number
	columnIndex: number
}
const spanMethod = ({ row, column, rowIndex, columnIndex }: SpanMethodProps) => {
	//合并前两列
	if (columnIndex === 0) {
		const _row = mergeRowCount.value[rowIndex];
		const _col = _row > 0 ? 1 : 0;
		return {
			rowspan: _row,
			colspan: _col
		}
	}
	if (columnIndex === 1) {
		const _row = mergeRowCount.value[rowIndex];
		const _col = _row > 0 ? 1 : 0;
		return {
			rowspan: _row,
			colspan: _col
		}
	}
}

html:

	<el-table :span-method="spanMethod"> ...