NPOI: how to read a file using NPOI

Question

I found NPOI to write Excel files very well with C #. But I want to open, read and change Excel files in C #.

How can i do this?

Answer 1

A simple reading example below:

using NPOI.HSSF.UserModel; using NPOI.SS.UserModel; //..... private void button1_Click(object sender, EventArgs e) { HSSFWorkbook hssfwb; using (FileStream file = new FileStream(@"c:\test.xls", FileMode.Open, FileAccess.Read)) { hssfwb= new HSSFWorkbook(file); } ISheet sheet = hssfwb.GetSheet("Arkusz1"); for (int row = 0; row <= sheet.LastRowNum; row++) { if (sheet.GetRow(row) != null) //null is when the row only contains empty cells { MessageBox.Show(string.Format("Row {0} = {1}", row, sheet.GetRow(row).GetCell(0).StringCellValue)); } } } 

By the way: on the NPOI site here in the Download section there is an example package - a package of C # examples. Try it if you haven't done it yet. :)

Answer 2

It might be useful to use the Workbook factory to instantiate the workbook object, as the factory method will do an xls or xlsx search for you. Link: http://apache-poi.1045710.n5.nabble.com/How-to-check-for-valid-excel-files-using-POI-without-checking-the-file-extension-td2341055.html

 IWorkbook workbook = WorkbookFactory.Create(inputStream); 

If you are not sure about the name of the sheet, but confident in the index (based on 0), you can grab the sheet as follows:

 ISheet sheet = workbook.GetSheetAt(sheetIndex); 

Then you can iterate over the lines using the code provided by the accepted answer from mj82

Answer 3

I find NPOI very useful for working with Excel files, here is my implementation (comments in Spanish, sorry for that):

This method Opens an Excel file (both xls or xlsx) and converts it to a DataTable.

  /// <summary>Abre un archivo de Excel (xls o xlsx) y lo convierte en un DataTable. /// LA PRIMERA FILA DEBE CONTENER LOS NOMBRES DE LOS CAMPOS.</summary> /// <param name="pRutaArchivo">Ruta completa del archivo a abrir.</param> /// <param name="pHojaIndex">Número (basado en cero) de la hoja que se desea abrir. 0 es la primera hoja.</param> private DataTable Excel_To_DataTable(string pRutaArchivo, int pHojaIndex) { // --------------------------------- // /* REFERENCIAS: * NPOI.dll * NPOI.OOXML.dll * NPOI.OpenXml4Net.dll */ // --------------------------------- // /* USING: * using NPOI.SS.UserModel; * using NPOI.HSSF.UserModel; * using NPOI.XSSF.UserModel; */ // AUTOR: Ing. Jhollman Chacon R. 2015 // --------------------------------- // DataTable Tabla = null; try { if (System.IO.File.Exists(pRutaArchivo)) { IWorkbook workbook = null; //IWorkbook determina si es xls o xlsx ISheet worksheet = null; string first_sheet_name = ""; using (FileStream FS = new FileStream(pRutaArchivo, FileMode.Open, FileAccess.Read)) { workbook = WorkbookFactory.Create(FS); //Abre tanto XLS como XLSX worksheet = workbook.GetSheetAt(pHojaIndex); //Obtener Hoja por indice first_sheet_name = worksheet.SheetName; //Obtener el nombre de la Hoja Tabla = new DataTable(first_sheet_name); Tabla.Rows.Clear(); Tabla.Columns.Clear(); // Leer Fila por fila desde la primera for (int rowIndex = 0; rowIndex <= worksheet.LastRowNum; rowIndex++) { DataRow NewReg = null; IRow row = worksheet.GetRow(rowIndex); IRow row2 = null; IRow row3 = null; if (rowIndex == 0) { row2 = worksheet.GetRow(rowIndex + 1); //Si es la Primera fila, obtengo tambien la segunda para saber el tipo de datos row3 = worksheet.GetRow(rowIndex + 2); //Y la tercera tambien por las dudas } if (row != null) //null is when the row only contains empty cells { if (rowIndex > 0) NewReg = Tabla.NewRow(); int colIndex = 0; //Leer cada Columna de la fila foreach (ICell cell in row.Cells) { object valorCell = null; string cellType = ""; string[] cellType2 = new string[2]; if (rowIndex == 0) //Asumo que la primera fila contiene los titlos: { for (int i = 0; i < 2; i++) { ICell cell2 = null; if (i == 0) { cell2 = row2.GetCell(cell.ColumnIndex); } else { cell2 = row3.GetCell(cell.ColumnIndex); } if (cell2 != null) { switch (cell2.CellType) { case CellType.Blank: break; case CellType.Boolean: cellType2[i] = "System.Boolean"; break; case CellType.String: cellType2[i] = "System.String"; break; case CellType.Numeric: if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType2[i] = "System.DateTime"; } else { cellType2[i] = "System.Double"; //valorCell = cell2.NumericCellValue; } break; case CellType.Formula: bool continuar = true; switch (cell2.CachedFormulaResultType) { case CellType.Boolean: cellType2[i] = "System.Boolean"; break; case CellType.String: cellType2[i] = "System.String"; break; case CellType.Numeric: if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType2[i] = "System.DateTime"; } else { try { //DETERMINAR SI ES BOOLEANO if (cell2.CellFormula == "TRUE()") { cellType2[i] = "System.Boolean"; continuar = false; } if (continuar && cell2.CellFormula == "FALSE()") { cellType2[i] = "System.Boolean"; continuar = false; } if (continuar) { cellType2[i] = "System.Double"; continuar = false; } } catch { } } break; } break; default: cellType2[i] = "System.String"; break; } } } //Resolver las diferencias de Tipos if (cellType2[0] == cellType2[1]) { cellType = cellType2[0]; } else { if (cellType2[0] == null) cellType = cellType2[1]; if (cellType2[1] == null) cellType = cellType2[0]; if (cellType == "") cellType = "System.String"; } //Obtener el nombre de la Columna string colName = "Column_{0}"; try { colName = cell.StringCellValue; } catch { colName = string.Format(colName, colIndex); } //Verificar que NO se repita el Nombre de la Columna foreach (DataColumn col in Tabla.Columns) { if (col.ColumnName == colName) colName = string.Format("{0}_{1}", colName, colIndex); } //Agregar el campos de la tabla: DataColumn codigo = new DataColumn(colName, System.Type.GetType(cellType)); Tabla.Columns.Add(codigo); colIndex++; } else { //Las demas filas son registros: switch (cell.CellType) { case CellType.Blank: valorCell = DBNull.Value; break; case CellType.Boolean: valorCell = cell.BooleanCellValue; break; case CellType.String: valorCell = cell.StringCellValue; break; case CellType.Numeric: if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; } else { valorCell = cell.NumericCellValue; } break; case CellType.Formula: switch (cell.CachedFormulaResultType) { case CellType.Blank: valorCell = DBNull.Value; break; case CellType.String: valorCell = cell.StringCellValue; break; case CellType.Boolean: valorCell = cell.BooleanCellValue; break; case CellType.Numeric: if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; } else { valorCell = cell.NumericCellValue; } break; } break; default: valorCell = cell.StringCellValue; break; } //Agregar el nuevo Registro if (cell.ColumnIndex <= Tabla.Columns.Count - 1) NewReg[cell.ColumnIndex] = valorCell; } } } if (rowIndex > 0) Tabla.Rows.Add(NewReg); } Tabla.AcceptChanges(); } } else { throw new Exception("ERROR 404: El archivo especificado NO existe."); } } catch (Exception ex) { throw ex; } return Tabla; } 

This second method makes oposite, saves the DataTable to an Excel file, yes, it can be xls or new xlsx, your choice!

  /// <summary>Convierte un DataTable en un archivo de Excel (xls o Xlsx) y lo guarda en disco.</summary> /// <param name="pDatos">Datos de la Tabla a guardar. Usa el nombre de la tabla como nombre de la Hoja</param> /// <param name="pFilePath">Ruta del archivo donde se guarda.</param> private void DataTable_To_Excel(DataTable pDatos, string pFilePath) { try { if (pDatos != null && pDatos.Rows.Count > 0) { IWorkbook workbook = null; ISheet worksheet = null; using (FileStream stream = new FileStream(pFilePath, FileMode.Create, FileAccess.ReadWrite)) { string Ext = System.IO.Path.GetExtension(pFilePath); //<-Extension del archivo switch (Ext.ToLower()) { case ".xls": HSSFWorkbook workbookH = new HSSFWorkbook(); NPOI.HPSF.DocumentSummaryInformation dsi = NPOI.HPSF.PropertySetFactory.CreateDocumentSummaryInformation(); dsi.Company = "Cutcsa"; dsi.Manager = "Departamento Informatico"; workbookH.DocumentSummaryInformation = dsi; workbook = workbookH; break; case ".xlsx": workbook = new XSSFWorkbook(); break; } worksheet = workbook.CreateSheet(pDatos.TableName); //<-Usa el nombre de la tabla como nombre de la Hoja //CREAR EN LA PRIMERA FILA LOS TITULOS DE LAS COLUMNAS int iRow = 0; if (pDatos.Columns.Count > 0) { int iCol = 0; IRow fila = worksheet.CreateRow(iRow); foreach (DataColumn columna in pDatos.Columns) { ICell cell = fila.CreateCell(iCol, CellType.String); cell.SetCellValue(columna.ColumnName); iCol++; } iRow++; } //FORMATOS PARA CIERTOS TIPOS DE DATOS ICellStyle _doubleCellStyle = workbook.CreateCellStyle(); _doubleCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("#,##0.###"); ICellStyle _intCellStyle = workbook.CreateCellStyle(); _intCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("#,##0"); ICellStyle _boolCellStyle = workbook.CreateCellStyle(); _boolCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("BOOLEAN"); ICellStyle _dateCellStyle = workbook.CreateCellStyle(); _dateCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("dd-MM-yyyy"); ICellStyle _dateTimeCellStyle = workbook.CreateCellStyle(); _dateTimeCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("dd-MM-yyyy HH:mm:ss"); //AHORA CREAR UNA FILA POR CADA REGISTRO DE LA TABLA foreach (DataRow row in pDatos.Rows) { IRow fila = worksheet.CreateRow(iRow); int iCol = 0; foreach (DataColumn column in pDatos.Columns) { ICell cell = null; //<-Representa la celda actual object cellValue = row[iCol]; //<- El valor actual de la celda switch (column.DataType.ToString()) { case "System.Boolean": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Boolean); if (Convert.ToBoolean(cellValue)) { cell.SetCellFormula("TRUE()"); } else { cell.SetCellFormula("FALSE()"); } cell.CellStyle = _boolCellStyle; } break; case "System.String": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.String); cell.SetCellValue(Convert.ToString(cellValue)); } break; case "System.Int32": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Numeric); cell.SetCellValue(Convert.ToInt32(cellValue)); cell.CellStyle = _intCellStyle; } break; case "System.Int64": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Numeric); cell.SetCellValue(Convert.ToInt64(cellValue)); cell.CellStyle = _intCellStyle; } break; case "System.Decimal": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Numeric); cell.SetCellValue(Convert.ToDouble(cellValue)); cell.CellStyle = _doubleCellStyle; } break; case "System.Double": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Numeric); cell.SetCellValue(Convert.ToDouble(cellValue)); cell.CellStyle = _doubleCellStyle; } break; case "System.DateTime": if (cellValue != DBNull.Value) { cell = fila.CreateCell(iCol, CellType.Numeric); cell.SetCellValue(Convert.ToDateTime(cellValue)); //Si No tiene valor de Hora, usar formato dd-MM-yyyy DateTime cDate = Convert.ToDateTime(cellValue); if (cDate != null && cDate.Hour > 0) { cell.CellStyle = _dateTimeCellStyle; } else { cell.CellStyle = _dateCellStyle; } } break; default: break; } iCol++; } iRow++; } workbook.Write(stream); stream.Close(); } } } catch (Exception ex) { throw ex; } } 

Using these two methods, you can open the Excel file, load it into the DataTable, make changes and save it back to the Excel file.

Hope you guys find this helpful.

Answer 4

 private DataTable GetDataTableFromExcel(String Path) { XSSFWorkbook wb; XSSFSheet sh; String Sheet_name; using (var fs = new FileStream(Path, FileMode.Open, FileAccess.Read)) { wb = new XSSFWorkbook(fs); Sheet_name= wb.GetSheetAt(0).SheetName; //get first sheet name } DataTable DT = new DataTable(); DT.Rows.Clear(); DT.Columns.Clear(); // get sheet sh = (XSSFSheet)wb.GetSheet(Sheet_name); int i = 0; while (sh.GetRow(i) != null) { // add neccessary columns if (DT.Columns.Count < sh.GetRow(i).Cells.Count) { for (int j = 0; j < sh.GetRow(i).Cells.Count; j++) { DT.Columns.Add("", typeof(string)); } } // add row DT.Rows.Add(); // write row value for (int j = 0; j < sh.GetRow(i).Cells.Count; j++) { var cell = sh.GetRow(i).GetCell(j); if (cell != null) { // TODO: you can add more cell types capatibility, eg formula switch (cell.CellType) { case NPOI.SS.UserModel.CellType.Numeric: DT.Rows[i][j] = sh.GetRow(i).GetCell(j).NumericCellValue; //dataGridView1[j, i].Value = sh.GetRow(i).GetCell(j).NumericCellValue; break; case NPOI.SS.UserModel.CellType.String: DT.Rows[i][j] = sh.GetRow(i).GetCell(j).StringCellValue; break; } } } i++; } return DT; } 

Answer 5

 private static ISheet GetFileStream(string fullFilePath) { var fileExtension = Path.GetExtension(fullFilePath); string sheetName; ISheet sheet = null; switch (fileExtension) { case ".xlsx": using (var fs = new FileStream(fullFilePath, FileMode.Open, FileAccess.Read)) { var wb = new XSSFWorkbook(fs); sheetName = wb.GetSheetAt(0).SheetName; sheet = (XSSFSheet) wb.GetSheet(sheetName); } break; case ".xls": using (var fs = new FileStream(fullFilePath, FileMode.Open, FileAccess.Read)) { var wb = new HSSFWorkbook(fs); sheetName = wb.GetSheetAt(0).SheetName; sheet = (HSSFSheet) wb.GetSheet(sheetName); } break; } return sheet; } private static DataTable GetRequestsDataFromExcel(string fullFilePath) { try { var sh = GetFileStream(fullFilePath); var dtExcelTable = new DataTable(); dtExcelTable.Rows.Clear(); dtExcelTable.Columns.Clear(); var headerRow = sh.GetRow(0); int colCount = headerRow.LastCellNum; for (var c = 0; c < colCount; c++) dtExcelTable.Columns.Add(headerRow.GetCell(c).ToString()); var i = 1; var currentRow = sh.GetRow(i); while (currentRow != null) { var dr = dtExcelTable.NewRow(); for (var j = 0; j < currentRow.Cells.Count; j++) { var cell = currentRow.GetCell(j); if (cell != null) switch (cell.CellType) { case CellType.Numeric: dr[j] = DateUtil.IsCellDateFormatted(cell) ? cell.DateCellValue.ToString(CultureInfo.InvariantCulture) : cell.NumericCellValue.ToString(CultureInfo.InvariantCulture); break; case CellType.String: dr[j] = cell.StringCellValue; break; case CellType.Blank: dr[j] = string.Empty; break; } } dtExcelTable.Rows.Add(dr); i++; currentRow = sh.GetRow(i); } return dtExcelTable; } catch (Exception e) { throw; } }