I am saving a file to the database with the codes below.

我正在用下面的代码将文件保存到数据库中。

controller.cs,

pk10.cs，

[HttpPost]
        public IActionResult AddFile(IFormFile file, TaskListAttachment taskListAttachment)
        {
            if (file != null && file.Length > 0)
            {
                var fileName = Path.Combine("wwwroot/files", Path.GetFileName(file.FileName));
                using (var stream = new FileStream(fileName, FileMode.Create))
                {
                    file.CopyTo(stream);
                }
                taskListAttachment.FileName = file.FileName;
                taskListAttachment.ContentType = file.ContentType;
                taskListAttachment.Data = new byte[file.Length];
                taskListAttachment.AddDateTime = DateTime.Now;
                taskListAttachment.FilePath = fileName;
                taskListAttachment.TaskId = Convert.ToInt32(Request.Form.Where(x => x.Key == "TaskId").FirstOrDefault().Value);
                taskListAttachment.AddUserId = Convert.ToInt32(Request.Form.Where(x => x.Key == "AddUserId").FirstOrDefault().Value);
                taskListAttachmentManager.itemAdd(taskListAttachment);
                var addValue = JsonConvert.SerializeObject(taskListAttachment);
                return Json(addValue);
            }
            else
            {
                return Json(null);
            }
        }

cshtml,

Cshtml，

<script>
        $("#fileInput").change(function () {
            var fileName = $(this).val();
            var fileExtension = fileName.split('.').pop().toLowerCase();
            $("#fileExtension").val(fileExtension);
        });

        $("#uploadButton").click(function () {
            var addUserId = $("#addUserId").data("user-id");
            var taskId = $("#taskId").data("task-id");
            var fileExtension = $("#fileExtension").val();
            var formData = new FormData();
            formData.append("AddUserId", addUserId);
            formData.append("TaskId", taskId);
            formData.append("FileExtension", fileExtension);
            formData.append("file", $("#fileInput")[0].files[0]);

            $.ajax({
                url: "/TaskList/AddFile/",
                type: "Post",
                data: formData,
                contentType: false,
                processData: false,
                success: function (result) {
                    var dismissModal = document.getElementById("dismissButton").click();
                    attachmentalert();
                    var FileInput = $('#fileInput');
                    FileInput.val('').focus();
                }
            });
        });
    </script>

I then wrote the following codes to download the saved file,

然后我编写了以下代码来下载保存的文件，

controller.cs,

Controler.cs

public IActionResult DownloadFile(int id)
        {
            var attachment = taskListAttachmentManager.itemGetById(id);
            if (attachment != null)
            {
                return File(attachment.Data, attachment.ContentType, attachment.FileName);
            }
            else
            {
                return NotFound();
            }
        }

cshtml,

Cshtml，

<a href="@Url.Action("DownloadFile", "TaskList", new {id = item.AttachmentID})" class="text-dark fs-4 link lh-sm">@item.FileName</a>

But when I download files, they download incorrectly or corrupted. If I download jpeg or png, the image won't open, if I download rar or zip, I get a warning that the archive is corrupt or incorrect. The same goes for office files and pdf.

但当我下载文件时，它们下载不正确或已损坏。如果我下载jpeg或png，图像将无法打开，如果我下载rar或压缩包，我会收到存档已损坏或不正确的警告。Office文件和pdf也是如此。

What is the problem?

有什么问题吗？

Thanks.

谢谢.