Error during updating the gridview?

Question

I got the below error message while updating the value on the gridview:

"Object reference not set to an instance of an object"

And my c# code is:

protected void gvDetails_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    int nmbr = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value.ToString());
    TextBox name = (TextBox)GridView1.Rows[e.RowIndex].FindControl("names");
    TextBox dept = (TextBox)GridView1.Rows[e.RowIndex].FindControl("depts");
    TextBox quantity = (TextBox)GridView1.Rows[e.RowIndex].FindControl("quantitys");
    con.Open();
    SqlCommand cmds=new SqlCommand("update erbp set name ='" + name.Text + "',dept ='"+ 
              dept.Text+"',quantity='" + quantity.Text + "' where inmbr=" + nmbr , con);
    cmds.ExecuteNonQuery();
    con.Close();
    GridView1.EditIndex = -1;
    BindEmployeeDetails();
}

A good practice is always to test if the FindControl is actually returning something. — emerson.marini, Jul 20 '13 at 09:55
In addition: a) use parameterized SQL; b) use `using` statements for SQL operations to clean up resources. — Jon Skeet, Jul 20 '13 at 09:58
the error is generated on the below line: SqlCommand cmds = new SqlCommand("update erbp set name ='" + name.Text + "',dept ='"+ dept.Text+"',quantity='" + quantity.Text + "' where inmbr=" + nmbr , con); — ram, Jul 20 '13 at 09:59
@ram it means that either of your controls name, dept or quantity is null. — Ehsan, Jul 20 '13 at 10:04
@Nithesh con cannot be the culprit here as it is open in the previous line. Had this been null it would have given error in the previous line. — Ehsan, Jul 20 '13 at 10:05
yesterday the same is executed correctly and today only i got this error sir @EhsanUllah — ram, Jul 20 '13 at 10:08
@EhsanUllah. ya you are correct. declare separate variables for `name`, `quantity` and assign corresponding values and check while debugging. Or try with `Convert.ToString()` inside the query part itself and check. — Nithesh Narayanan, Jul 20 '13 at 10:08
@ram place your debugger over this line and see which control is null. VS compiler cannot be wrong — Ehsan, Jul 20 '13 at 10:09

score 0 · Answer 1 · answered Jul 20 '13 at 10:46

you need to update your code to check that controls that you have assigned from gridview are not null. Do some exception handling as well.

protected void gvDetails_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
  try
  {
  int nmbr = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value.ToString());
  TextBox name = (TextBox)GridView1.Rows[e.RowIndex].FindControl("names");
  TextBox dept = (TextBox)GridView1.Rows[e.RowIndex].FindControl("depts");
  TextBox quantity = (TextBox)GridView1.Rows[e.RowIndex].FindControl("quantitys");
  //do check that any of your controls here is not null
  if(name!=null && dept!=null && quantity !=null)
  {
      con.Open();
      SqlCommand cmds=new SqlCommand("update erbp set name ='" + name.Text + "',dept ='"+ 
          dept.Text+"',quantity='" + quantity.Text + "' where inmbr=" + nmbr , con);
      cmds.ExecuteNonQuery();
      con.Close();
      GridView1.EditIndex = -1;
      BindEmployeeDetails();
  }
  }
  catch(Exception ex)       
  {
      //do exception handling here. 
  }
}

Error during updating the gridview?

1 Answers1