你调用的对象是空的。错误显示使用gridview中的文件上载控件 [英] Object reference not set to an instance of an object. error show using file upload control in gridview

问题描述

  protected   void  Button1_Click（对象发​​件人，EventArgs e）
 {
 
按钮Button1 =（按钮）发件人; 
 GridViewRow gvRow =（GridViewRow）Button1.NamingContainer; 
 FileUpload fuCOA =（FileUpload）gvRow.FindControl（  FileUpload1）; 
 Stream fs = fuCOA.PostedFile.InputStream; 
 BinaryReader br =  new  BinaryReader（fs）; 
  Byte  [] bytes = br.ReadBytes（（ Int32 ）fs.Length）; 
标签ID =（（标签）gvRow.FindControl（  lblApplicantNo））; 
  string  sql_update =  @  update ApplicantData set ApplicantFile = @ ApplicantFile; 
 sql_update + =  其中ApplicantNo = @ ApplicantNo; 
 SqlCommand cmdDist =  new  SqlCommand（sql_update，con）; 
 
 cmdDist.Parameters.Add（  @ ApplicantFile，SqlDbType.Binary ）.Value = bytes; 
 cmdDist.Parameters.AddWithValue（  @ ApplicantNo，ID.Text.ToString（） ）; 
 con.Open（）; 
  int  i = cmdDist.ExecuteNonQuery（）; 
 con.Close（）; 
  if （i >   0 ）
 {
 Response.Redirect（  ApplicantExamUpdate.aspx） ; 
} 
 
} 

解决方案

使用调试器：拼写错误的机会可能是FileUpload1 错了，它在这一行找不到：

 FileUpload fuCOA =（FileUpload）gvRow.FindControl（   FileUpload1）; 

如果不是这样，那很可能就是没有可用的文件 - 但你需要使用调试器来确切地确定你的语句的哪个部分是空的。

我们不能为你做那个 - 我们可以;运行你的代码！

protected void Button1_Click(object sender, EventArgs e)
        {
           
            Button Button1 = (Button)sender;
            GridViewRow gvRow = (GridViewRow)Button1.NamingContainer;
            FileUpload fuCOA = (FileUpload)gvRow.FindControl("FileUpload1");
            Stream fs = fuCOA.PostedFile.InputStream;
            BinaryReader br = new BinaryReader(fs);
            Byte[] bytes = br.ReadBytes((Int32)fs.Length);
            Label ID = ((Label)gvRow.FindControl("lblApplicantNo"));
            string sql_update = @" update ApplicantData set ApplicantFile=@ApplicantFile";
            sql_update += " where ApplicantNo=@ApplicantNo";
             SqlCommand cmdDist = new SqlCommand(sql_update, con);
            
             cmdDist.Parameters.Add("@ApplicantFile", SqlDbType.Binary).Value = bytes;
             cmdDist.Parameters.AddWithValue("@ApplicantNo", ID.Text.ToString());
                con.Open();
                int i = cmdDist.ExecuteNonQuery();
                con.Close();
                if (i > 0)
                {
                    Response.Redirect("ApplicantExamUpdate.aspx");
                }
           
        }

解决方案

Use the debugger: The chances are that you spelt "FileUpload1" wrong and it can't find it in this line:

FileUpload fuCOA = (FileUpload)gvRow.FindControl("FileUpload1");

If it isn't that, then it's likely that there is no file available - but you need to use the debugger to find out exactly which part of your statement is null to be sure.
We can't do that for you - we can;t run your code!

这篇关于你调用的对象是空的。错误显示使用gridview中的文件上载控件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！