I am getting this error->Object reference not set to an instance of an object.

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I want to download a file from database using gridview

Here is my code...

C#

protected void Page_Load(object sender, EventArgs e)
       {
           if (!IsPostBack)
           {
               BindGrid();
           }
       }
       private void BindGrid()
       {
           string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
           using (SqlConnection con = new SqlConnection(constr))
           {
               using (SqlCommand cmd = new SqlCommand())
               {
                   cmd.CommandText = "select Id, FileName from Career";
                   cmd.Connection = con;
                   con.Open();
                   cmd.ExecuteNonQuery();
                   GridView1.DataBind();
                   con.Close();
               }
           }

       }




       protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
       {
           {
               int id = int.Parse((sender as LinkButton).CommandArgument);
               byte[] bytes;
               string fileName, contentType;
               string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
               using (SqlConnection con = new SqlConnection(constr))
               {
                   using (SqlCommand cmd = new SqlCommand())
                   {
                       cmd.CommandText = "select FileName, Data, contentType from Career where Id=@Id";
                       cmd.Parameters.AddWithValue("@Id", id);
                       cmd.Connection = con;
                       con.Open();
                       using (SqlDataReader sdr = cmd.ExecuteReader())
                       {
                           sdr.Read();
                           bytes = (byte[])sdr["Data"];
                           contentType = sdr["contentType"].ToString();
                           fileName = sdr["FileName"].ToString();
                       }
                       con.Close();
                   }
               }
               Response.Clear();
               Response.Buffer = true;
               Response.Charset = "";
               Response.Cache.SetCacheability(HttpCacheability.NoCache);
               Response.ContentType = contentType;
               Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName);
               Response.BinaryWrite(bytes);
               Response.Flush();
               Response.End();
           }
       }

   }

Please let me know how to solve this error??

Update: The error occurs on this line

C#

int id = int.Parse((sender as LinkButton).CommandArgument);

Posted 12-Aug-15 0:27am

RMSinha

Updated 12-Aug-15 1:14am

F-ES Sitecore

v2

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Comments

RAJKUMAR M G 12-Aug-15 6:37am

Specify the error line

F-ES Sitecore 12-Aug-15 6:38am

You solve the error but not referencing null variables. How you fix your *specific* error depends on what it is that is null that you're referencing but as you didn't say what line the error occurred on it's impossible to give any specific help, you're asking people to guess.

MohamedEliyas 12-Aug-15 6:38am

specify the error line in your code. mention pls

RMSinha 12-Aug-15 6:47am

ohh sorry its my fault...

Sanket Saxena 12-Aug-15 6:47am

Debug it first and let us know where you are facing the issue.

RMSinha 13-Aug-15 2:18am

Thank you so much everyone...its really work

2 solutions

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Animesh Datta · Answer 1 · 2015-08-12T00:58:00

Hello ,
You have not used GridView DataSource property .Modify your code like this way

using (SqlCommand cmd = new SqlCommand())
               {
                   cmd.CommandText = "select Id, FileName from Career";
                   cmd.Connection = con;
                   con.Open();

                //Remove this line
	           //  cmd.ExecuteNonQuery();

	               //Add these lines
         	       DataTable dt = new DataTable();
                   dt.Load(cmd.ExecuteReader());
                
	             GridView1.DataSource=dt;
              
	             GridView1.DataBind();
                 con.Close();
               }

Sanket Saxena · Answer 2 · 2015-08-12T01:09:00

Could you please check and change your code as below:

C#

 protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
  {    
    if (e.CommandName == "YourButtonCommandName")

       {
           int id = Convert.ToInt32(e.CommandArgument.ToString());

           //rest code here

       }
}

Hope it Helps :)

I am getting this error->Object reference not set to an instance of an object.

2 solutions

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Solution 3

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