ASP .NET RowUpdating GridView Troubles

I’m having trouble with the RowUpdating Method. My GridView is connected to our local SQL Server, and I’m trying to update the data. Here is the code for the RowUpdating Method from MSDN.

protected void TaskGridView_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
        //Retrieve the table from the session object.
        DataTable dt = (DataTable)Session["TaskTable"];

        //Update the values.
        GridViewRow row = GridView1.Rows[e.RowIndex];
        dt.Rows[row.DataItemIndex]["Id"] = ((TextBox)(row.Cells[1].Controls[0])).Text;
        dt.Rows[row.DataItemIndex]["Description"] = ((TextBox)(row.Cells[2].Controls[0])).Text;
        dt.Rows[row.DataItemIndex]["IsComplete"] = ((CheckBox)(row.Cells[3].Controls[0])).Checked;

        //Reset the edit index.
        GridView1.EditIndex = -1;

        //Bind data to the GridView control.
        BindData();

}

I get this error:

System.NullReferenceException: Object reference not set to an instance of an object.

Answers:

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Method 1

try this code once.

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
    int id = Int32.Parse(GridView1.DataKeys[e.RowIndex].Value.ToString());
    TextBox tname = (TextBox)row.FindControl("nam");
    TextBox tques = (TextBox)row.FindControl("que");
    MySqlCommand cmd = new MySqlCommand("update exam set <a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="147a7579712529547a757971">[email protected]</a>,<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="b5c4c0d0c688f5c4c0d0c6">[email protected]</a> where id = @id", con);
    cmd.Parameters.Add("@id", MySqlDbType.Int16).Value = id;
    cmd.Parameters.Add("@name", MySqlDbType.VarChar, 30).Value = tname.Text.Trim();
    cmd.Parameters.Add("@ques", MySqlDbType.VarChar,40).Value = tques.Text.Trim();
    con.Open();
    cmd.ExecuteNonQuery();
    GridView1.EditIndex = -1;
    bind();
}

Method 2

Not all GridViewRow have a DataItem.

You should add a if block around your code and verify the row being updated is of type DataRow.

if (e.Row.RowType == DataControlRowType.DataRow)
{
     your code here...
}

More regarding RowTypes : http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridviewrow.rowtype.aspx

Method 3

public void bindGvEdit()
{
    GridView1.DataSource = obj1.SelectAlltbl();
    GridView1.DataBind();
}

protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
    GridView1.EditIndex = e.NewEditIndex;
    bindGvEdit();
}

protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
    GridView1.EditIndex = -1;
    bindGvEdit();
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = GridView1.Rows[e.RowIndex];
    obj1.Id = Convert.ToInt32(GridView1.DataKeys[row.RowIndex].Value);
    obj1.Name = ((TextBox)row.Cells[1].Controls[1]).Text;
    obj1.Description = ((TextBox)row.Cells[2].Controls[1]).Text;
    obj1.Updatetbl();
    GridView1.EditIndex = -1;
    bindGvEdit();
}

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0