[OpenXml] Read/Write row/cell from excel

        public static void test(){
            using (SpreadsheetDocument document = SpreadsheetDocument.Open("test.xlsx", true))
            {
                WorkbookPart workbookPart = document.WorkbookPart;

                string relId = workbookPart.Workbook.Descendants<Sheet>().First(sheet => sheet.Name.Value.ToLower().Equals("sheet1")).Id;
                WorksheetPart worksheetpart = (WorksheetPart)workbookPart.GetPartById(relId);

                DocumentFormat.OpenXml.Spreadsheet.Worksheet worksheet = worksheetpart.Worksheet;
                SheetData sheetData = worksheet.GetFirstChild<SheetData>();

                for (int i = 2; i <= 3; i++)
                {
                    Row row = new Row() { RowIndex = (uint)i };
                    row.Append(new Cell() { CellReference = "A" + i, DataType = CellValues.String, CellValue = new CellValue("kaka") });//, StyleIndex = styleIndex });
                    row.Append(new Cell() { CellReference = "B" + i, DataType = CellValues.String, CellValue = new CellValue("2") });//, StyleIndex = styleIndex });
                    row.Append(new Cell() { CellReference = "C" + i, DataType = CellValues.String, CellValue = new CellValue("GENERAL MANAGEMENT") });//, StyleIndex = styleIndex });
                    row.Append(new Cell() { CellReference = "D" + i, DataType = CellValues.String, CellValue = new CellValue("2") });//, StyleIndex = styleIndex });
                    row.Append(new Cell() { CellReference = "E" + i, DataType = CellValues.String, CellValue = new CellValue((1 == 1).ToString()) });//, StyleIndex = styleIndex });
                    sheetData.Append(row);
                }

                // loop each row to get value;
                string cellValue = GetCellValue(sheetData.Descendants<Row>().ElementAt<Row>(0), "A", getSharedString(document));

                worksheet.Save();
            }
        }

        private static List<SharedStringItem> getSharedString(SpreadsheetDocument document)
        {
            WorkbookPart workbookPart = document.WorkbookPart;
            return workbookPart.SharedStringTablePart.SharedStringTable.Elements<SharedStringItem>().ToList<SharedStringItem>();
        }

        // cell could be null
        private static Cell GetCell(Row row, string columnName)
        {
            return row.Descendants<Cell>().FirstOrDefault(p => p.CellReference == columnName + row.RowIndex);
        }

        // call getSharedString
        // call GetCell
        // => retrieve cell value
        public static string GetCellValue(Row row, string columnName, List<SharedStringItem> sharedStrings)
        {
            Cell cell = GetCell(row, columnName);

            if (cell == null)
            {
                return null;
            }

            string value = "";

            if (cell.DataType != null && cell.DataType.Value == CellValues.SharedString)
            {
                SharedStringItem item = sharedStrings.ElementAt<SharedStringItem>(Int32.Parse(cell.CellValue.Text));
                value = item.InnerText;
            }
            else
            {
                value = cell.CellValue.Text;
            }
            return value;
        }