C# – Exporting datagridview to csv file

c++datagridviewstreamwriter

I'm working on a application which will export my DataGridView called scannerDataGridView to a csv file.

Found some example code to do this, but can't get it working. Btw my datagrid isn't databound to a source.

When i try to use the Streamwriter to only write the column headers everything goes well, but when i try to export the whole datagrid including data i get an exeption trhown.

System.NullReferenceException: Object reference not set to an instance
of an object. at Scanmonitor.Form1.button1_Click(Object sender,
EventArgs e)

Here is my Code, error is given on the following line:

dataFromGrid = dataFromGrid + ',' + dataRowObject.Cells[i].Value.ToString();

//csvFileWriter = StreamWriter
//scannerDataGridView = DataGridView   

private void button1_Click(object sender, EventArgs e)
{
    string CsvFpath = @"C:\scanner\CSV-EXPORT.csv";
    try
    {
        System.IO.StreamWriter csvFileWriter = new StreamWriter(CsvFpath, false);

        string columnHeaderText = "";

        int countColumn = scannerDataGridView.ColumnCount - 1;

        if (countColumn >= 0)
        {
            columnHeaderText = scannerDataGridView.Columns[0].HeaderText;
        }

        for (int i = 1; i <= countColumn; i++)
        {
            columnHeaderText = columnHeaderText + ',' + scannerDataGridView.Columns[i].HeaderText;
        }


        csvFileWriter.WriteLine(columnHeaderText);

        foreach (DataGridViewRow dataRowObject in scannerDataGridView.Rows)
        {
            if (!dataRowObject.IsNewRow)
            {
                string dataFromGrid = "";

                dataFromGrid = dataRowObject.Cells[0].Value.ToString();

                for (int i = 1; i <= countColumn; i++)
                {
                    dataFromGrid = dataFromGrid + ',' + dataRowObject.Cells[i].Value.ToString();

                    csvFileWriter.WriteLine(dataFromGrid);
                }
            }
        }


        csvFileWriter.Flush();
        csvFileWriter.Close();
    }
    catch (Exception exceptionObject)
    {
        MessageBox.Show(exceptionObject.ToString());
    }

Best Solution

LINQ FTW!

var sb = new StringBuilder();

var headers = dataGridView1.Columns.Cast<DataGridViewColumn>();
sb.AppendLine(string.Join(",", headers.Select(column => "\"" + column.HeaderText + "\"").ToArray()));

foreach (DataGridViewRow row in dataGridView1.Rows)
{
    var cells = row.Cells.Cast<DataGridViewCell>();
    sb.AppendLine(string.Join(",", cells.Select(cell => "\"" + cell.Value + "\"").ToArray()));
}

And indeed, c.Value.ToString() will throw on null value, while c.Value will correctly convert to an empty string.

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