Question

我正在尝试将数据库中的所有用户导出到excel文件。

运行此代码并调试后，我没有遇到任何错误，并且LetsExcelAll（）方法一直处于运行状态。不知道我在想什么。代码运行完毕后，不会遇到任何错误，也不会开始下载。

控制器：

public void LetsExcelAll()
    {
        try
        {
            var userRepo = new UsersRepository();
            XLWorkbook wb = null;

            wb = userRepo.DownloadUsers();

            Response.Clear();
            Response.Buffer = true;
            Response.Charset = "";
            Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

            Response.AddHeader("content-disposition", "attachment;filename=Users.xlsx");

            using (MemoryStream MyMemoryStream = new MemoryStream())
            {
                wb.SaveAs(MyMemoryStream);
                MyMemoryStream.WriteTo(Response.OutputStream);
                Response.Flush();
                Response.End();
            }
        }
        catch(Exception ex)
        {
            throw ex;
        }
    }

REPO：

public XLWorkbook DownloadUsers()
    {
        try
        {
            if (thisConnection.State == ConnectionState.Closed)
                thisConnection.Open();

            MySqlCommand download = thisConnection.CreateCommand();

            download.CommandText = UserQueries.DownloadUsers;


            using (MySqlDataAdapter sda = new MySqlDataAdapter())
            {
                sda.SelectCommand = download;
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    using (XLWorkbook wb = new XLWorkbook())
                    {
                        var ws = wb.Worksheets.Add(dt, "ALL_Users");
                        ws.Columns().AdjustToContents();
                        ws.Columns().Style.Alignment.SetWrapText();

                        return wb;

                    }
                }
            }
        }
        catch(Exception ex)
        {
            throw ex;
        }
        finally
        {
            thisConnection.Close();
        }
    }

视图：（如何调用该方法）

    $("#downloadAllUsers").click(function () {
    $.post("/Users/LetsExcelAll")                    
});

Answer 1

您不能直接返回文件作为jQuery.post()方法的响应。必须将文件以字节数组的形式存储在TempData或Session状态下，并将其传递给标记为HttpGetAttribute的另一个控制器，以便用户下载文件。

要执行以下步骤：

1）更改LetsExcelAll方法以返回包含文件名的JsonResult并将MemoryStream的输出存储在TempData / Session变量内，并具有如下所示的某些键

[HttpPost]
public ActionResult LetsExcelAll()
{
    try
    {
        var userRepo = new UsersRepository();
        XLWorkbook wb = null;

        wb = userRepo.DownloadUsers();

        using (MemoryStream MyMemoryStream = new MemoryStream())
        {
            wb.SaveAs(MyMemoryStream);

            // set stream to starting position
            MyMemoryStream.Position = 0;

            // store file contents inside TempData
            TempData["ExcelFile"] = MyMemoryStream.ToArray();
        }

        // return file name as JSON data
        return new JsonResult() { Data = new { FileName = "Users.xlsx", Status = "Success" } };
    }
    catch(Exception ex)
    {
        throw ex;
    }

    return new JsonResult() { Data = new { Status = "Nothing" } };
}

2）在AJAX window.location响应中设置POST以将文件名作为使用GET的操作方法名称的查询字符串参数（假设downloadAllUsers是一个按钮元素）

$("#downloadAllUsers").click(function () {
    $.post("/Users/LetsExcelAll", function(data) {
        if (data.Status == "Success") {
            window.location = '/Users/DownloadFile?fileName=' + data.FileName;
        }
    });
});

3）使用文件名作为输入参数，用HttpGetAttribute创建一个新控制器，并从中返回FileResult。

[HttpGet]
public ActionResult DownloadFile(string fileName)
{
    if (TempData["ExcelFile"] != null)
    {
        var data = TempData["ExcelFile"] as byte[];
        string contentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

        return File(data, contentType, fileName);
    }
    else
    {
        // if TempData messing up, return nothing
        return new EmptyResult();
    }
}

从这一点来看，文件下载应该可以正常工作。

Excel导出在MVC中不起作用。没有错误被抛出

1 个答案: