0

I'm stucked with a System.NullReferenceException when I'm trying to delete the lonely row of a datatable, displayed in a datagridview by using a button click. This datatable is within a dataset, who's generated from XLM schema and XML file. But, if I have more than 1 line in this datatable, I can delete the selected one without throwing any exception.

I explored a lot of posts on stackoverflow but anyone of them could help me !

I give you the portion of code who's throwing the exception :

private void button4_Click(object sender, EventArgs e)
{
        DialogResult removeLocationChoice = MessageBox.Show("Are you sure you want to delete this location ?", "Remove location ?", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
        if (removeLocationChoice == DialogResult.Yes)
        {
            // Get the index of the currentrow from datagridview1
            int currentIndex = (this.dataGridView1.CurrentRow.Index);
            // Remove the selected row into the dataset
            Functions.settingsDataSet.Tables["Location"].Rows[currentIndex].Delete();
            // Commit changes to dataset
            Functions.settingsDataSet.Tables["Location"].AcceptChanges();
            // Commit changes from dataset to XML file
            Functions.commitXml();
        }
}

FYI I use Visual Studio 2010.

I found these strange values with the debugger :

Functions.settingsDataSet.Tables["Location"].Rows[currentIndex].newRecord = -1
.RowState = Detached

Don't hesitate to ask me for more information and other portions of code. I suspect an error due to headers but I'm not sure about that.

Ok so new update : I found a solution but not the best ! I remove my table form the dataset and then I reapply the XML schema to recover my table without any rows :

public static void removeRow(string table, int row)
    {
        if (row == 0)
        {
            settingsDataSet.Tables.Remove(table);
            settingsDataSet.ReadXmlSchema(settingsSchema);
            settingsDataSet.AcceptChanges();
        }
        else
        {
            settingsDataSet.Tables[table].Rows.RemoveAt(row);
            settingsDataSet.Tables[table].AcceptChanges();
        }
        commitXml();
    }

By this way I don't have any exception any more. If you have better solution, please comment or reply on this post !! :-)

Brian Tompsett - 汤莱恩
  • 5,753
  • 72
  • 57
  • 129
Tim Christin
  • 13
  • 4
  • 1
    [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) – Soner Gönül Jul 24 '14 at 13:33
  • What do you have debugger for? – Tarec Jul 24 '14 at 13:34
  • I use Visual Studio 2010 – Tim Christin Jul 24 '14 at 13:47
  • Thanks for the link for NullReferenceException but I can't find which value is null... – Tim Christin Jul 24 '14 at 14:45
  • _The Lonely Row_ sounds like a Film noir title. Maybe it refers to the extra row shown when you have `myDataGridView1.AllowUserToAddRows = true` ..? Set it to false then.. – TaW Jul 24 '14 at 15:30
  • Sorry for the strange title but i prefer this word instead of "last row" :-) it's not about that. But it could be ! In fact if I have 2 filled rows, I can delete one row without throwing exception. But after that, if I want to remove the last one I get the exception... – Tim Christin Jul 24 '14 at 16:06

0 Answers0