How to lock some excel columns as readonly for npoi excel sheet

Question

unable to set npoi excel sheet as read only for some columns I have tried create freeze (sheet1.CreateFreezePane(0, 1, 0, 1);) but not working

    public void WriteExcelWithNPOI(DataTable dt, String extension,string MSANAme,string CheckValue)
    {

        IWorkbook workbook;

        if (extension == "xlsx")
        {
            workbook = new XSSFWorkbook();
        }
        else if (extension == "xls")
        {
            workbook = new HSSFWorkbook();
        }
        else
        {
            throw new Exception("This format is not supported");
        }

        ISheet sheet1 = workbook.CreateSheet("Sheet 1");
        //make a header row
        IRow row1 = sheet1.CreateRow(0);



        for (int j = 0; j < dt.Columns.Count; j++)
        {

            ICell cell = row1.CreateCell(j);
            String columnName = dt.Columns[j].ToString();
            cell.SetCellValue(columnName);
        }

        //loops through data
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            IRow row = sheet1.CreateRow(i + 1);
            for (int j = 0; j < dt.Columns.Count; j++)
            {

                ICell cell = row.CreateCell(j);
                String columnName = dt.Columns[j].ToString();
                cell.SetCellValue(dt.Rows[i][columnName].ToString());
            }
        }

        using (var exportData = new MemoryStream())
        {
            Response.Clear();
            workbook.Write(exportData);
            if (extension == "xlsx") //xlsx file format
            {
                Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}" + MSANAme + CheckValue+ ".xlsx"));

                Response.BinaryWrite(exportData.ToArray());
            }
            else if (extension == "xls")  //xls file format
            {
                Response.ContentType = "application/vnd.ms-excel";
                Response.AddHeader("Content-Disposition", string.Format("attachment;filename="+ MSANAme + CheckValue + ".xls"));
                Response.BinaryWrite(exportData.GetBuffer());
            }
            Response.End();
        }
    }

all the excel columns are editable, need to set some of the columns as readonly. please help. all the excel columns are editable, need to set some of the columns as readonly. please help. all the excel columns are editable, need to set some of the columns as readonly. please help.

Answer 1

Am going to assume your code is working, so am taking it as reference and editing it.

    public void WriteExcelWithNPOI(DataTable dt, String extension,string MSANAme,string CheckValue)
    {

        IWorkbook workbook;

        if (extension == "xlsx")
        {
            workbook = new XSSFWorkbook();
        }
        else if (extension == "xls")
        {
            workbook = new HSSFWorkbook();
        }
        else
        {
            throw new Exception("This format is not supported");
        }

        ISheet sheet1 = workbook.CreateSheet("Sheet 1");
        //make a header row
        IRow row1 = sheet1.CreateRow(0);

        var cellStyleForLocked = workbook.CreateCellStyle(); //create the style in the beginning itself
        cellStyleForLocked.IsLocked = true;

        for (int j = 0; j < dt.Columns.Count; j++)
        {

            ICell cell = row1.CreateCell(j);
            String columnName = dt.Columns[j].ToString();
            cell.SetCellValue(columnName);
        }

        //loops through data
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            IRow row = sheet1.CreateRow(i + 1);
            for (int j = 0; j < dt.Columns.Count; j++)
            {

                ICell cell = row.CreateCell(j);
                String columnName = dt.Columns[j].ToString();

                if(j < 6) //set the locked style only for first 6 columns.
                    cell.CellStyle = cellStyleForLocked;

                cell.SetCellValue(dt.Rows[i][columnName].ToString());
            }
        }

        using (var exportData = new MemoryStream())
        {
            Response.Clear();
            workbook.Write(exportData);
            if (extension == "xlsx") //xlsx file format
            {
                Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}" + MSANAme + CheckValue+ ".xlsx"));

                Response.BinaryWrite(exportData.ToArray());
            }
            else if (extension == "xls")  //xls file format
            {
                Response.ContentType = "application/vnd.ms-excel";
                Response.AddHeader("Content-Disposition", string.Format("attachment;filename="+ MSANAme + CheckValue + ".xls"));
                Response.BinaryWrite(exportData.GetBuffer());
            }
            Response.End();
        }
    }

Hopefully it works for you!