c# (WinForms-App) export DataSet to Excel

Question

I need a solution to export a dataset to an excel file without any asp code (HttpResonpsne...) but i did not find a good example to do this...

Best thanks in advance

Answer 1

I've created a class that exports a DataGridView or DataTable to an Excel file. You can probably change it a bit to make it use your DataSet instead (iterating through the DataTables in it). It also does some basic formatting which you could also extend.

To use it, simply call ExcelExport, and specify a filename and whether to open the file automatically or not after exporting. I also could have made them extension methods, but I didn't. Feel free to.

Note that Excel files can be saved as a glorified XML document and this makes use of that.

EDIT: This used to use a vanilla StreamWriter , but as pointed out, things would not be escaped correctly in many cases. Now it uses a XmlWriter , which will do the escaping for you.

The ExcelWriter class wraps an XmlWriter . I haven't bothered, but you might want to do a bit more error checking to make sure you can't write cell data before starting a row, and such. The code is below.

public class ExcelWriter : IDisposable
{
    private XmlWriter _writer;

    public enum CellStyle { General, Number, Currency, DateTime, ShortDate };

    public void WriteStartDocument()
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteProcessingInstruction("mso-application", "progid=\"Excel.Sheet\"");
        _writer.WriteStartElement("ss", "Workbook", "urn:schemas-microsoft-com:office:spreadsheet");
         WriteExcelStyles();
   }

    public void WriteEndDocument()
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteEndElement();
    }

    private void WriteExcelStyleElement(CellStyle style)
    {
        _writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
        _writer.WriteEndElement();
    }

    private void WriteExcelStyleElement(CellStyle style, string NumberFormat)
    {
        _writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");

        _writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
        _writer.WriteStartElement("NumberFormat", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteAttributeString("Format", "urn:schemas-microsoft-com:office:spreadsheet", NumberFormat);
        _writer.WriteEndElement();

        _writer.WriteEndElement();

    }

    private void WriteExcelStyles()
    {
        _writer.WriteStartElement("Styles", "urn:schemas-microsoft-com:office:spreadsheet");

        WriteExcelStyleElement(CellStyle.General);
        WriteExcelStyleElement(CellStyle.Number, "General Number");
        WriteExcelStyleElement(CellStyle.DateTime, "General Date");
        WriteExcelStyleElement(CellStyle.Currency, "Currency");
        WriteExcelStyleElement(CellStyle.ShortDate, "Short Date");

        _writer.WriteEndElement();
    }

    public void WriteStartWorksheet(string name)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteStartElement("Worksheet", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteAttributeString("Name", "urn:schemas-microsoft-com:office:spreadsheet", name);
        _writer.WriteStartElement("Table", "urn:schemas-microsoft-com:office:spreadsheet");
    }

    public void WriteEndWorksheet()
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteEndElement();
        _writer.WriteEndElement();
    }

    public ExcelWriter(string outputFileName)
    {
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Indent = true;
        _writer = XmlWriter.Create(outputFileName, settings);
    }

    public void Close()
    {
        if (_writer == null) throw new InvalidOperationException("Already closed.");

        _writer.Close();
        _writer = null;
    }

    public void WriteExcelColumnDefinition(int columnWidth)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteStartElement("Column", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteStartAttribute("Width", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteValue(columnWidth);
        _writer.WriteEndAttribute();
        _writer.WriteEndElement();
    }

    public void WriteExcelUnstyledCell(string value)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");
        _writer.WriteValue(value);
        _writer.WriteEndElement();
        _writer.WriteEndElement();
    }

    public void WriteStartRow()
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteStartElement("Row", "urn:schemas-microsoft-com:office:spreadsheet");
    }

    public void WriteEndRow()
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteEndElement();
    }

    public void WriteExcelStyledCell(object value, CellStyle style)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        _writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");
        _writer.WriteAttributeString("StyleID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
        _writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");
        switch (style)
        {
            case CellStyle.General:
                _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");
                break;
            case CellStyle.Number:
            case CellStyle.Currency:
                _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "Number");
                break;
            case CellStyle.ShortDate:
            case CellStyle.DateTime:
                _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "DateTime");
                break;
        }
        _writer.WriteValue(value);
        //  tag += String.Format("{1}\"><ss:Data ss:Type=\"DateTime\">{0:yyyy\\-MM\\-dd\\THH\\:mm\\:ss\\.fff}</ss:Data>", value,

        _writer.WriteEndElement();
        _writer.WriteEndElement();
    }

    public void WriteExcelAutoStyledCell(object value)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");

        //write the <ss:Cell> and <ss:Data> tags for something
        if (value is Int16 || value is Int32 || value is Int64 || value is SByte ||
            value is UInt16 || value is UInt32 || value is UInt64 || value is Byte)
        {
            WriteExcelStyledCell(value, CellStyle.Number);
        }
        else if (value is Single || value is Double || value is Decimal) //we'll assume it's a currency
        {
            WriteExcelStyledCell(value, CellStyle.Currency);
        }
        else if (value is DateTime)
        {
            //check if there's no time information and use the appropriate style
            WriteExcelStyledCell(value, ((DateTime)value).TimeOfDay.CompareTo(new TimeSpan(0, 0, 0, 0, 0)) == 0 ? CellStyle.ShortDate : CellStyle.DateTime);
        }
        else
        {
            WriteExcelStyledCell(value, CellStyle.General);
        }
    }

    #region IDisposable Members

    public void Dispose()
    {
        if (_writer == null)
            return;

        _writer.Close();
        _writer = null;
    }

    #endregion
}

Then you can export your DataTable using the following:

public static void ExcelExport(DataTable data, String fileName, bool openAfter)
{
    //export a DataTable to Excel
    DialogResult retry = DialogResult.Retry;

    while (retry == DialogResult.Retry)
    {
        try
        {
            using (ExcelWriter writer = new ExcelWriter(fileName))
            {
                writer.WriteStartDocument();

                // Write the worksheet contents
                writer.WriteStartWorksheet("Sheet1");

                //Write header row
                writer.WriteStartRow();
                foreach (DataColumn col in data.Columns)
                    writer.WriteExcelUnstyledCell(col.Caption);
                writer.WriteEndRow();

                //write data
                foreach (DataRow row in data.Rows)
                {
                    writer.WriteStartRow();
                    foreach (object o in row.ItemArray)
                    {
                        writer.WriteExcelAutoStyledCell(o);
                    }
                    writer.WriteEndRow();
                }

                // Close up the document
                writer.WriteEndWorksheet();
                writer.WriteEndDocument();
                writer.Close();
                if (openAfter)
                    OpenFile(fileName);
                retry = DialogResult.Cancel;
            }
        }
        catch (Exception myException)
        {
            retry = MessageBox.Show(myException.Message, "Excel Export", MessageBoxButtons.RetryCancel, MessageBoxIcon.Asterisk);
        }
    }
}

Answer 2

The following site demonstrates how to export a DataSet (or DataTable or List<>) into a " genuine " Excel 2007 .xlsx file.

It uses the OpenXML libraries, so you don't need to have Excel installed on your server.

C# ExportToExcel library

All of the source code is provided, free of charge , along with instructions using it with ASP.NET, ASP.NET Core 2+ or regular C#.

It's very easy to add to your own applications, you just need to call one function, passing in an Excel filename, and your data source:

DataSet ds = CreateSampleData();
string excelFilename = "C:\\Sample.xlsx";
CreateExcelFile.CreateExcelDocument(ds, excelFilename);

Hope this helps.

Answer 3

using XL = Microsoft.Office.Interop.Excel;
using System.Reflection;

public static void Datasource(DataTable dt)
{
    XL.Application oXL;
    XL._Workbook oWB;
    XL._Worksheet oSheet;
    XL.Range oRng;

    try
    {
        oXL = new XL.Application();
        Application.DoEvents();
        oXL.Visible = false;

        //Get a new workbook.
        oWB = (XL._Workbook)(oXL.Workbooks.Add(Missing.Value));
        oSheet = (XL._Worksheet)oWB.ActiveSheet;

        //System.Data.DataTable dtGridData=ds.Tables[0];

        int iRow = 2;
        if (dt.Rows.Count > 0)
        {
            for (int j = 0; j < dt.Columns.Count; j++)
            {
                oSheet.Cells[1, j + 1] = dt.Columns[j].ColumnName;
            }

            // For each row, print the values of each column.
            for (int rowNo = 0; rowNo < dt.Rows.Count; rowNo++)
            {
                for (int colNo = 0; colNo < dt.Columns.Count; colNo++)
                {
                    oSheet.Cells[iRow, colNo + 1] = dt.Rows[rowNo][colNo].ToString();
                }
                iRow++;
            }
            iRow++;
        }
        oRng = oSheet.get_Range("A1", "IV1");
        oRng.EntireColumn.AutoFit();
        oXL.Visible = true;
    }
    catch (Exception theException)
    {
        throw theException;
    }
    finally
    {
        oXL = null;
        oWB = null;
        oSheet = null;
        oRng = null;
    }
}

Import from Excel to datatable:

 DataTable dtTable = new DataTable();
 DataColumn col = new DataColumn("Rfid");
 dtTable.Columns.Add(col);
 DataRow drRow;

 Microsoft.Office.Interop.Excel.Application ExcelObj =
        new Microsoft.Office.Interop.Excel.Application();
 Microsoft.Office.Interop.Excel.Workbook theWorkbook =
            ExcelObj.Workbooks.Open(txt_FilePath.Text, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                                    Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                                    Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
 Microsoft.Office.Interop.Excel.Sheets sheets = theWorkbook.Worksheets;
 try
 {
     for (int sht = 1; sht <= sheets.Count; sht++)
     {
          Microsoft.Office.Interop.Excel.Worksheet worksheet =
                    (Microsoft.Office.Interop.Excel.Worksheet)sheets.get_Item(sht);

          for (int i = 2; i <= worksheet.UsedRange.Rows.Count; i++)
          {
              Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range("A" + i.ToString(), "B" + i.ToString());
              System.Array myvalues = (System.Array)range.Cells.Value2;
              String name = Convert.ToString(myvalues.GetValue(1, 1));
              if (string.IsNullOrEmpty(name) == false)
              {
                  drRow = dtTable.NewRow();
                  drRow["Rfid"] = name;
                  dtTable.Rows.Add(drRow);
              }
          }
              Marshal.ReleaseComObject(worksheet);
              worksheet = null;
        }
    return dtTable;
}
catch
{
    throw;
}
finally
{
   // Marshal.ReleaseComObject(worksheet);
    Marshal.ReleaseComObject(sheets);
    Marshal.ReleaseComObject(theWorkbook);
    Marshal.ReleaseComObject(ExcelObj);
    //worksheet = null;
    sheets = null;
    theWorkbook = null;
    ExcelObj = null;
}

Answer 4

This was a post with a really helpful top answer, but I found it was lacking because there was no simple way to import the XML file back into a datatable. I ended up having to write my own, and thought I would share it here in case anyone else was in the same boat (google was exceptionally unhelpful in that regard):

public static DataTable ImportExcelXML(string Filename)
    {
        //create a new dataset to load in the XML file
        DataSet DS = new DataSet();
        //Read the XML file into the dataset
        DS.ReadXml(Filename);
        //Create a new datatable to store the raw Data
        DataTable Raw = new DataTable();
        //assign the raw data from the file to the datatable
        Raw = DS.Tables["Data"];
        //count the number of columns in the XML file
        int ColumnNumber = Raw.Columns.Count;
        //create a datatable to store formatted Import Data
        DataTable ImportData = new DataTable();
        //create a string list to store the cell data of each row
        List<string> RowData = new List<string>();
        //loop through each row in the raw data table
        for (int Counter = 0; Counter < Raw.Rows.Count; Counter++)
        {
            //if the data in the row is a colum header
            if (Counter < ColumnNumber)
            {
                //add the column name to our formatted datatable
                ImportData.Columns.Add(Raw.Rows[Counter].ItemArray.GetValue(1).ToString());
            }
            else
            {
                //if the row # (1 row = 1 cell from the excel file) from the raw datatable is divisable evenly by the number of columns in the formated import datatable AND this is not the 1st row of the raw table data after the headers
                if ((Counter % ColumnNumber == 0) && (Counter != ColumnNumber))
                {
                    //add the row we just built to the formatted import datatable
                    ImportData.Rows.Add(GenerateRow(ImportData, RowData));
                    //clear rowdata list in preperation for the next row
                    RowData.Clear();
                }
                //add the current cell data value from the raw datatable to the string list of cell values for the next row to be added to the formatted input datatable
                RowData.Add(Raw.Rows[Counter].ItemArray.GetValue(1).ToString());
            }
        }
        //add the final row
        ImportData.Rows.Add(GenerateRow(ImportData, RowData));

        return ImportData;
    }

    public static DataRow GenerateRow(DataTable ImportData, List<string> RowData)
    {
        //create a counter to keep track of the column position during row composition
        int ColumnPosition = 0;
        //make a new datarow based on the schema of the formated import datatable
        DataRow NewRow = ImportData.NewRow();
        //for each string cell value collected for the RowData list for this row
        foreach (string CellData in RowData)
        {
            //add the cell value to the new datarow
            NewRow[ImportData.Columns[ColumnPosition].ColumnName] = CellData;
            //incriment column position in the new row
            ColumnPosition++;
        }
        //return the generated row
        return NewRow;
    }

Answer 5

the code have problem with null values.

 public void WriteExcelAutoStyledCell(object value)
    {
        //solve null values
        if (value is DBNull) return;

Answer 6

I would have added this to the comments but I am new to stack so I am unable to comment. Using lc.'s solution I added another function that tests the strings characters for invalid XML characters. When I was exporting to excel on occasion there were characters that were found that were causing the export to fail.

You will need to modify one of the functions that is in lc's code.

public void WriteExcelAutoStyledCell(object value)
    {
        if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
        string newValue = string.Empty;

        try
        {
            //write the <ss:Cell> and <ss:Data> tags for something
            if (value is Int16 || value is Int32 || value is Int64 || value is SByte ||
                value is UInt16 || value is UInt32 || value is UInt64 || value is Byte)
            {
                WriteExcelStyledCell(value, CellStyle.Number);
            }
            else if (value is Single || value is Double || value is Decimal) //we'll assume it's a currency
            {
                WriteExcelStyledCell(value, CellStyle.Currency);
            }
            else if (value is DateTime)
            {
                //check if there's no time information and use the appropriate style
                WriteExcelStyledCell(value, ((DateTime)value).TimeOfDay.CompareTo(new TimeSpan(0, 0, 0, 0, 0)) == 0 ? CellStyle.ShortDate : CellStyle.DateTime);
            }
            else
            {
                newValue = CheckXmlCompatibleValues(value.ToString()).ToString();
                WriteExcelStyledCell(newValue, CellStyle.General);
            }
        }
        catch (Exception thisException)
        {
            throw new InvalidOperationException(thisException.Message.ToString());
        }
    }

And add this function to 'ExcelWriter' class

public string CheckXmlCompatibleValues(string value)
    {
        string newValue = string.Empty;
        bool found = false;

        foreach (char c in value)
        {
            if (XmlConvert.IsXmlChar(c))
                newValue += c.ToString();
            else
                found = true;
        }

        return newValue.ToString();
    }

lc. Thanks for the code!

Answer 7

Creating excel files in .NET applications is quite common and similar questions have been asked several times before. For instance here and here . The last question asks about reading excel files, but most suggested solutions should work both ways.

Answer 8

Microsoft has a built in solution for Importing/Exporting Excel files. It's not the most straightforward library but it generally works better than the others listed above.

The library required to do this is included in Office and can be found under the list of Framework assemblies at Microsoft.Office.Interop.Excel.

Here is some example code:

using Excel = Microsoft.Office.Interop.Excel;

Excel.Application app = new Excel.Application();

//Open existing workbook
//Excel.Workbook workbook = xlApp.Workbooks.Open(fileName);

//Create new workbook
Excel.Workbook workbook = app.Workbooks.Add();

Excel.Worksheet worksheet = workbook.ActiveSheet;

worksheet.Cells[1,1] = "Hello world!"; // Indexes start at 1, because Excel
workbook.SaveAs("C:\\MyWorkbook.xlsx");
workbook.Close();
app.Quit();