How to create CSV from select columns in Datagrid?

Question

 if (!Directory.Exists("C:\\VIES"))
        {
            Directory.CreateDirectory("C:\\VIES");
        }
        dgRecords1.SelectAllCells();
        dgRecords1.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;

        ApplicationCommands.Copy.Execute(null, dgRecords1);
        dgRecords1.UnselectAllCells();
        String result = (string)Clipboard.GetData(DataFormats.CommaSeparatedValue);
        try
        {
            StreamWriter sw = new StreamWriter("C:\\VIES\\VIESReport.CSV", false);
            sw.WriteLine(result);
            sw.Close();
            Process.Start("C:\\VIES\\VIESReport.CSV");
        }

In this code above, I select all records in the datagrid along with headers and write this to a csv file. What I need to do is that I need only two columns to be in the csv. Is there a way of doing that?

Answer 1

You can use the following code which converts datatable to csv. The code is very flexible like you can change the column name and can select number of columns.

To export to csv you need to call this

ExportFile.ExportCSV(dt, "id,name", "Product ID,Name","order.csv");

The class file is below

public class ExporFile
{
    /// <summary>
    /// Export to CSV
    /// </summary>
    /// <param name="exportTable">Export table</param>
    /// <param name="showColumns">Columns needs to show in CSV</param>
    /// <param name="changedColumnName">Changed Column Names in CSV</param>
    /// <param name="fileName">File Name</param>
    public static void ExportCSV(DataTable exportTable, string showColumns, string changedColumnName, string fileName)
    {
        DataTable filterTable = FilterColumn(exportTable, showColumns, changedColumnName);
        string dataCSV = DataTable2CSV(filterTable, "\t", "\"");
        dataCSV = System.Web.HttpContext.Current.Server.HtmlDecode(dataCSV);
        System.Web.HttpContext.Current.Response.Charset = "";
        System.Web.HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.Unicode;
        System.Web.HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=" + fileName);
        System.Web.HttpContext.Current.Response.Write(dataCSV);
        System.Web.HttpContext.Current.Response.Flush();
        try
        {
            System.Web.HttpContext.Current.Response.End();
        }
        catch { };
    }

    /// <summary>
    /// Filter Columns
    /// </summary>
    /// <param name="exportTable"></param>
    /// <param name="showColumns"></param>
    /// <param name="changedColumnName"></param>
    /// <returns></returns>
    private static DataTable FilterColumn(DataTable exportTable, string showColumns, string changedColumnName)
    {
        DataView filterDataView = exportTable.DefaultView;
        //filterDataView.Sort = "AutoID";
        DataTable filterTable = filterDataView.ToTable(false, showColumns.Split(','));
        return ChangedExportDataColumnName(filterTable, changedColumnName);
    }

    /// <summary>
    /// Changed Column Datatable
    /// </summary>
    /// <param name="filterTable"></param>
    /// <param name="changedColumnName"></param>
    /// <returns></returns>
    private static DataTable ChangedExportDataColumnName(DataTable filterTable, string changedColumnName)
    {
        string[] changedNames = changedColumnName.Split(',');

        for (int i = 0; i < changedNames.Length; i++)
        {
            if (!String.IsNullOrEmpty(changedNames[i]))
            {
                filterTable.Columns[i].ColumnName = changedNames[i];
            }
        }
        return filterTable;
    }

    /// <summary>
    /// Returns a CSV string corresponding to a datatable. However the separator can be defined and hence it can be any string separated value and not only csv.
    /// </summary>
    /// <param name="table">The Datatable</param>
    /// <param name="separator">The value separator</param>
    /// <param name="circumfix">The circumfix to be used to enclose values</param>
    /// <returns></returns>
    private static String DataTable2CSV(DataTable table, string separator, string circumfix)
    {

        StringBuilder builder = new StringBuilder(Convert.ToString((char)65279));
        foreach (DataColumn col in table.Columns)
        {
            builder.Append(col.ColumnName).Append(separator);
        }
        builder.Remove((builder.Length - separator.Length), separator.Length);
        builder.Append(Environment.NewLine);

        foreach (DataRow row in table.Rows)
        {
            foreach (DataColumn col in table.Columns)
            {
                builder.Append(circumfix).Append(row[col.ColumnName].ToString().Replace("\"", "\"\"")).Append(circumfix).Append(separator);
            }
            builder.Remove((builder.Length - separator.Length), separator.Length);
            builder.Append(Environment.NewLine);
        }
        return builder.ToString();
    }
}