How to insert a date to an Open XML worksheet?

Question

I\'m using Microsoft Open XML SDK 2 and I\'m having a really hard time inserting a date into a cell. I can insert numbers without a problem by setting Cell.DataType = Cell

Answer 1

There are 2 ways to store dates in OpenXml; by writing a number (using ToOADate) and setting the DataType to Number or by writing an ISO 8601 formatted date and setting the DataType to Date. Note that the default DataType is Number so if you go with the first option you don't have to set the DataType.

Whichever method you choose, you'll need to set the style as Excel displays both methods identically. The following code shows an example of writing a date using the Number format (with and without explicitly setting the DataType) and using the ISO 8601 format.

using (SpreadsheetDocument document = SpreadsheetDocument.Create(filename, SpreadsheetDocumentType.Workbook))
{
    //fluff to generate the workbook etc
    WorkbookPart workbookPart = document.AddWorkbookPart();
    workbookPart.Workbook = new Workbook();

    var worksheetPart = workbookPart.AddNewPart();
    worksheetPart.Worksheet = new Worksheet();

    Sheets sheets = workbookPart.Workbook.AppendChild(new Sheets());

    Sheet sheet = new Sheet() { Id = workbookPart.GetIdOfPart(worksheetPart), SheetId = 1, Name = "Sheet" };
    sheets.Append(sheet);

    workbookPart.Workbook.Save();

    var sheetData = worksheetPart.Worksheet.AppendChild(new SheetData());

    //add the style
    Stylesheet styleSheet = new Stylesheet();

    CellFormat cf = new CellFormat();
    cf.NumberFormatId = 14;
    cf.ApplyNumberFormat = true;

    CellFormats cfs = new CellFormats();
    cfs.Append(cf);
    styleSheet.CellFormats = cfs;

    styleSheet.Borders = new Borders();
    styleSheet.Borders.Append(new Border());
    styleSheet.Fills = new Fills();
    styleSheet.Fills.Append(new Fill());
    styleSheet.Fonts = new Fonts();
    styleSheet.Fonts.Append(new Font());

    workbookPart.AddNewPart();
    workbookPart.WorkbookStylesPart.Stylesheet = styleSheet;

    CellStyles css = new CellStyles();
    CellStyle cs = new CellStyle();
    cs.FormatId = 0;
    cs.BuiltinId = 0;
    css.Append(cs);
    css.Count = UInt32Value.FromUInt32((uint)css.ChildElements.Count);
    styleSheet.Append(css);

    Row row = new Row();

    DateTime date = new DateTime(2017, 6, 24);

    /*** Date code here ***/
    //write an OADate with type of Number
    Cell cell1 = new Cell();
    cell1.CellReference = "A1";
    cell1.CellValue = new CellValue(date.ToOADate().ToString());
    cell1.DataType = new EnumValue(CellValues.Number);
    cell1.StyleIndex = 0;
    row.Append(cell1);

    //write an OADate with no type (defaults to Number)
    Cell cell2 = new Cell();
    cell2.CellReference = "B1";
    cell2.CellValue = new CellValue(date.ToOADate().ToString());
    cell1.StyleIndex = 0;
    row.Append(cell2);

    //write an ISO 8601 date with type of Date
    Cell cell3 = new Cell();
    cell3.CellReference = "C1";
    cell3.CellValue = new CellValue(date.ToString("yyyy-MM-dd"));
    cell3.DataType = new EnumValue(CellValues.Date);
    cell1.StyleIndex = 0;
    row.Append(cell3);

    sheetData.AppendChild(row);

    worksheetPart.Worksheet.Save();
}