Question

我有以下代码：

    [Authorize]
    [HttpGet]
    public FileContentResult DownloadMsgAsPdf(string FileId, string outer = "")
    {
        var Results = (SearchResult)TempData["Results"];
        var msg = Results.emails[FileId];
...
        return File(pdfBytes, System.Net.Mime.MediaTypeNames.Application.Octet, msg.Id + ".pdf");
     }

现在运行一次（点击一个链接）它完全可以。但是，在第二次单击它时（没有其他任何更改或调用），它会出错，结果为null。我认为这意味着TempData正在被清除，但这怎么可能呢？

如果需要，这是完整的代码：

    [Authorize]
    [HttpGet]
    public FileContentResult DownloadMsgAsPdf(string FileId, string outer = "")
    {
        var Results = (SearchResult)TempData["Results"];
        var msg = Results.emails[FileId];

        TempData.Keep();

        msg.BodyHTML = System.Web.HttpUtility.HtmlDecode(msg.BodyHTML);

        var htmlContent = String.Format("<center><p><b>Case ID</b>: " + msg.Id
        + "   <b>User ID</b>: " + Session["userid"]
        + "   <b>Privileged</b>: ");
        if (msg.Tags != null)
        {
            htmlContent += msg.Tags.ContainsKey("privileged");
        }
        else
        {
            htmlContent += "False";
        }
        htmlContent += "   <b>Downloaded</b>: " + DateTime.Now.ToString("g") + "</center>"
        + " <p> -- Forwarded message -- </p> "
        + " <p><b> From :</b> <a href='#'>" + msg.From + "</a> </p> "
        + " <p><b> Date:</b> Mon, oct 25 2010 at 4:42 PM  </p> "
        + " <p> <b>Subject:</b> " + msg.Subject + " </p> "
        + " <p><b> To:</b> " + msg.To + " </p> "
        + " <p><b> Cc: </b> </p> "
        + " <div> "
        + " <ul> ";
        if(msg.attachementList != null){
            if (!msg.attachementList.Any())
            {
                htmlContent += "<text> "
                + "<li><label style='color:gray'>No attachment</label></li></text>";
            }
            else
            {
                foreach (var attachment in msg.attachementList)
                {
                    var filename = System.IO.Path.GetFileName(attachment);
                    htmlContent += "<text> "
                    + "<li><a href='#'>" + filename + "</a></li></text>";
                }
            }
        }
        htmlContent += "</ul>"
        + "</div>"
        + "<div padding: 5px;'>"
        + msg.BodyText
        + "</div>"
        + "</div>";

        var pdfBytes = (new NReco.PdfGenerator.HtmlToPdfConverter()).GeneratePdf(htmlContent);

        if (outer != "")
        {
            return File(pdfBytes, System.Net.Mime.MediaTypeNames.Application.Octet, msg.Id + ".pdf");
        }

        return new FileContentResult(pdfBytes, "application/pdf");
    }

Answer 1

TempData意味着你只能获得一次。我看到你使用TempData.Keep()，但这种方法只影响同一个http上下文。我认为您可以使用Session或Cache代替TempData。

TempData不保留FileContentResult中的值

1 个答案: