EPPlus ignoring fractional seconds?

Question

Using EPPlus to write the contents of a datagrid to an Excel file. This function:

public static void FormatExcelCell(OfficeOpenXml.ExcelRange cellExcel,
                                   object cellValue, 
                                   System.Type cellValueType, 
                                   bool UseAlternateDateFormat = false)
{
    cellExcel.Value = cellValue;
    if (cellValue.ToString() != Constants.ValueForMissingTag)
    {
        if (cellValueType == typeof(System.DateTime))
            cellExcel.Style.Numberformat.Format = 
            UseAlternateDateFormat ?
            Constants.FormatDateTimeAlternateExport : 
            Constants.FormatDateTime;
    }
    else
    {
        cellExcel.Style.Fill.PatternType = 
                                    OfficeOpenXml.Style.ExcelFillStyle.Solid;
        cellExcel.Style.Fill.BackgroundColor.SetColor
                                              (Constants.ColorForMissingTag);
    }
}

If the format string is set to "yyyy-MM-dd HH:mm:ss.ff", then the dates in the Excel file look like this: 2018-06-18 15:45:25.ff

If the format string is set to "yyyy-MM-dd HH:mm:ss.00", then the dates in the Excel file look like this: 2018-06-18 15:45:25.00

Is EPPlus removing the fraction of a second (I know it's there because I can see it in the datagrid), or is it mangling the format string somehow? Is this a bug? Is there a workaround?

Thanks.

Update: updated EPPlus from 4.1.0.1 to 4.5.2.1 and added OpenXML which wasn't previously needed; still produces wrong datetime formats as above.

Answer 1

Here how I do it in my code. This is a Extension method.

    public static void SetCellDateTimeWithMsValue(this ExcelRange cell, DateTime? value)
    {
        cell.Style.Numberformat.Format = "yyyy-MM-dd HH:mm:ss.000";
        if (!value.HasValue) return;
        cell.Value = value.Value;
    }