Asp.NET Core 導出數據到 Excel 文件

在Asp.Net Core開發中，使用NPOI將數據導出到Excel文件中，並返回給前端。

service 層代碼：

        /// <summary>
        /// 將數據導出到excel
        /// </summary>
        /// <param name="projectId"></param>
        /// <param name="ids"></param>
        /// <returns></returns>
        public async Task<IWorkbook> ExportToExcel(Guid projectId, List<Guid> ids = null)
        {
            var entities = await attendanceRecordRepository.Find(x =>
                                                x.ProjectId == projectId)
                                                .ToListAsync();

            if (entities == null || entities.Count == 0) return null;

            //創建工作簿
            IWorkbook workbook = new XSSFWorkbook();
            ISheet sheet = workbook.CreateSheet("考勤記錄");

            //添加表頭
            IRow tableHeader = sheet.CreateRow(0);
            var colNames = new List<string>()
            {
                "姓名", "身份證號", "工號", "人員類型", "辦公室", "工種", "電話號碼", "狀態", "打卡時間"
            };
            for (int i = 0; i < colNames.Count; i++)
            {
                tableHeader.CreateCell(i).SetCellValue(colNames[i]);
                // 自適應寬高
                sheet.AutoSizeColumn(i);
            }

            // 將數據寫入表格中
            if (ids == null || ids.Count == 0)
            {
                // 導出全部
                for (int i = 0; i < entities.Count; i++)
                {
                    // 跳過表頭
                    var row = sheet.CreateRow(i + 1);

                    row.CreateCell(0).SetCellValue(entities[i].Name);
                    row.CreateCell(1).SetCellValue(entities[i].ID_card);
                    row.CreateCell(2).SetCellValue(entities[i].EmployeeNumber);
                    row.CreateCell(3).SetCellValue(entities[i].PersonnelType);
                    row.CreateCell(4).SetCellValue(entities[i].OfficeLocation);
                    row.CreateCell(5).SetCellValue(entities[i].PostName);
                    row.CreateCell(6).SetCellValue(entities[i].PhoneNumber);
                    row.CreateCell(7).SetCellValue(entities[i].Type);
                    row.CreateCell(8).SetCellValue(entities[i].CreateTime.ToString("yyyy-MM-dd HH:mm:ss"));
                }
            }
            else
            {
                // 導出部分
                int rowIndex = 1;
                foreach (var entity in entities)
                {
                    foreach (var id in ids)
                    {
                        if (entity.Id == id)
                        {
                            var row = sheet.CreateRow(rowIndex);

                            row.CreateCell(0).SetCellValue(entity.Name);
                            row.CreateCell(1).SetCellValue(entity.ID_card);
                            row.CreateCell(2).SetCellValue(entity.EmployeeNumber);
                            row.CreateCell(3).SetCellValue(entity.PersonnelType);
                            row.CreateCell(4).SetCellValue(entity.OfficeLocation);
                            row.CreateCell(5).SetCellValue(entity.PostName);
                            row.CreateCell(6).SetCellValue(entity.PhoneNumber);
                            row.CreateCell(7).SetCellValue(entity.Type);
                            row.CreateCell(8).SetCellValue(entity.CreateTime.ToString("yyyy-MM-dd HH:mm:ss"));

                            rowIndex++;
                        }
                    }
                }
            }

            return workbook;
        }

controller 層代碼： 

        /// <summary>
        /// 將數據導出為Excel文件
        /// </summary>
        /// <param name="projectId"></param>
        /// <param name="ids"></param>
        /// <returns></returns>
        [HttpPost("export-to-excel")]
        public async Task<IActionResult> ExportToExcel(Guid projectId, List<Guid> ids = null)
        {
            var workbook = await _attendanceRecordService.ExportToExcel(projectId, ids);

            if(workbook != null)
            {
                var path = Path.Combine(webHostEnvironment.ContentRootPath, "FileName");
                if (!Directory.Exists(path)) //沒有此路徑就新建
                {
                    Directory.CreateDirectory(path);
                }
                var fileFullName = Path.Combine(path, $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.xlsx");

                // 將表格寫入文件流
                FileStream creatStream = new FileStream(fileFullName, FileMode.Create, FileAccess.Write);
                workbook.Write(creatStream);
                creatStream.Close();

                // 將表格文件轉換成可讀的文件流
                FileStream fileStream = new FileStream(fileFullName, FileMode.Open, FileAccess.Read, FileShare.Read); //讀

                // 將可讀文件流寫入 byte[]
                byte[] bytes = new byte[fileStream.Length];
                fileStream.Read(bytes, 0, bytes.Length);
                fileStream.Close();

                // 把 byte[] 轉換成 Stream （創建其支持存儲區為記憶體的流。）
                MemoryStream stream = new(bytes);

                try
                {
                    return File(stream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                            $"{DateTime.Now.ToString("yyyyMMddHHmmss")}考勤記錄");
                }
                finally
                {
                    System.IO.File.Delete(fileFullName);
                }
                
            }
            return BadRequest();
        }