C#回傳檔案無法下載Excel檔案

我正在嘗試使用 MVC 專案下載這樣的檔案：

控制器：

  [HttpPost]
        [ActionName("ExportList")]
        public async Task<IActionResult> ExportList(List<object> objectList)
        {
            var fileName = "fileName" ".xlsx";
            try
            {
                var fileContent = await _serviceLayer.ExportListToExcel(objectList);
                return File(fileContent, "application/vnd.ms-excel", fileName);
                // return new JsonResult("ok");
            }
            catch(Exception ex)
            {
                return BadRequest(ex.Message);
            }
        } 

然后我的服務層：

public Task<byte[]> ExportListToExcel(List<object> objectList)
        {
            try
            {
               using(var workbook = new XLWorkbook())
                {
                    var worksheet = workbook.Worksheets.Add("Report");
                    var currentRow = 1;

                    #region Header
                    worksheet.Cell(currentRow, 1).Value = "val1";
                    worksheet.Cell(currentRow, 2).Value = "val2";
                    worksheet.Cell(currentRow, 3).Value = "val3";
                    #endregion

                    #region Body
                    foreach(var obj in objectList)
                    {
                        currentRow  ;
                        worksheet.Cell(currentRow, 1).Value = obj.val1;
                        worksheet.Cell(currentRow, 2).Value = obj.val2;
                        worksheet.Cell(currentRow, 3).Value = obj.val3;
                    }
                    #endregion

                    using(var stream = new MemoryStream())
                    {
                        workbook.SaveAs(stream);
                        var content = stream.ToArray();

                        return Task.FromResult(content);
                    }
                }
            }
            catch (Exception ex)
            {
                throw new Exception("Error");
            }
        }

我用ajax呼叫控制器方法：

 function exportList() {
                 $.ajax({
                    type: "POST",
                    url: "@Url.Action("ExportList")",
                     data: { objectList: objectList},
                    dataType: "json",
                    success: function (data) {
                       //show success message
                    }, error: function (req, status, error) {
                       //show error message
                  }
            });
        }

我閱讀了很多帖子，這基本上是他們建議下載檔案的內容，但是我回傳視圖并顯示以下錯誤訊息并且檔案沒有被下載但控制器沒有拋出任何型別的例外訊息：

有什么想法下載檔案嗎？

uj5u.com熱心網友回復：

試試Blob responseType，

$.ajax({
   type: "POST",
   url: "@Url.Action("ExportList")",
   data: { objectList: objectList},
   xhrFields: {
      responseType: 'blob' // FileContentResult will return as blob
   },
   success: function (data) {
      const url = window.URL.createObjectURL(data); // create url from blob
      const link = document.createElement('a'); // create anchor at DOM
      link.href = url; 
      link.setAttribute('download', 'file.xlsx'); // download attribute
      document.body.appendChild(link);
      link.click(); // trigger click for download
   },
   error: function (req, status, error) {
      //show error message
   }
});

uj5u.com熱心網友回復：

嗨，您的問題是您的 javascript 函式 exportList() 最好在檔案所在的位置創建一個重定向，然后下載它。在您的匯出方法中

這將是您的 ExportList 控制器方法的一部分：

// Generate a new unique identifier against which the file can be stored
                string handle = Guid.NewGuid().ToString();    
                using (MemoryStream memoryStream = new MemoryStream())
                {
                   //save your file to memory stream
                    workbook.SaveAs(memoryStream);
                    memoryStream.Position = 0;
                    TempData[handle] = memoryStream.ToArray();
                }
    
                // Note we are returning a filename as well as the handle
                return new JsonResult()
                {
                    Data = new { FileGuid = handle, FileName = "exporfile.xlsx" , FileType="xlsx"}
                };

您的下載檔案應如下所示：

 public virtual ActionResult Download(string fileGuid, string fileName, string fileType)
        {
            if (TempData[fileGuid] != null)
            {
                byte[] data = TempData[fileGuid] as byte[];
                if (fileType == "xlsx" || fileType == "xls")
                {
                    return File(data, "application/vnd.ms-excel", fileName);
                }
                else if (fileType == "pdf")
                {
                    return File(data, "application/pdf", fileName);
                }
                else
                {
                    //sin especificar...
                    return File(data, "application/octet-stream", fileName);
                }
            }
            else
            {
               
                return new EmptyResult();
            }
        }

然后更改您的匯出串列方法：

 function exportList() {
                 $.ajax({
                    type: "POST",
                    url: "@Url.Action("ExportList")",
                     data: { objectList: objectList},
                    dataType: "json",
                    success: function (data) {
                       var response = JSON.parse(data);
                    window.location = '/YourController/Download?fileGuid='   response.FileGuid   '&filename='   response.FileName  '&fileType='   response.FileType;
                    }, error: function (req, status, error) {
                       //show error message
                  }
        });
    }

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