使用C＃在asp.net中没有得到在ViewState中的价值？ [英] Not getting value in Viewstate in asp.net using C#?

问题描述

我使用的是asyncfileupload控制上传文件有我走路径视图状态是这样的：

I am using a asyncfileupload control to upload a file there i am taking the path in a view state like this:

protected void ProcessUpload(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e)
{
    string name = System.IO.Path.GetFileName(e.FileName); 
    string dir = Server.MapPath("upload_eng/");
    string path = Path.Combine(dir, name);
    ViewState["path"] = path;
    engcertfupld.SaveAs(path);
}

现在，当我试图保存在ButtonClick事件我没有得到视图状态的值路径：

Now when i am trying to save that path in a buttonclick event i am not getting the value of viewstate:

protected void btnUpdate_Click(object sender, EventArgs e)
{
   string filepath = ViewState["path"].ToString(); // GETTING NULL in filepath
}

在此文件路径我得到空其实我得到错误空引用异常

In this filepath i am getting null actually i am getting error NULL REFERENCE EXCEPTION

现在我该怎么办？

推荐答案

把路径值在的对话 对象，而不是ViewState中，像这样的：

Put the Path value in the Session object instead of the ViewState, like this:

protected void ProcessUpload(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e)
{

    ....
    string path = Path.Combine(dir, name);
    Session["path"] = path;
}

然后在按钮点击：

Then in the Button Click:

protected void btnUpdate_Click(object sender, EventArgs e)
{
  if (Session["path"] != null)
  {
     string filepath = (string) Session["path"];
  }
}

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