Blazor Export Excel based on template excel file C#

 Target:

i have mudtable contains data from model object.

i need when user press on export excel button to load object data for mudtable to ready excel file template and write data for this template then download it for end user on the browser.

Used Nuget: NPOI version 2.6.0

Create custom component for export excel ExportExcel.razor

@inherits BaseComponentCustom

<a href="" @onclick="Export" class="btn btn-white btn-sm  shadow-sm fw-bold" data-bs-toggle="modal" data-bs-target="#kt_share">

    @trans["ExportData"]

    <!--begin:: Icon-->

    <img src="assets/media/svg/icon/share-qoute.svg" class="h-25px">

    <!--end:: Icon-->

</a>

*-------------------------------------------------------------------------------

using NPOI.SS.UserModel;

using NPOI.XSSF.UserModel;

namespace YourNameSpace;

public partial class ExportExcel

{

    private FileStream _file;

    [Parameter] public ExcelDataObject? ExcelDataObject{ get; set; }

    private async void Export()

    {

        if (ExcelDataObject!= null)

        {

            string rootpath = Path.Combine(System.IO.Directory.GetCurrentDirectory(), "wwwroot/assets/Templates/");

            string name = "TemplateFile.xlsx";

            string FileName = Path.Combine(rootpath, name);

            IWorkbook _workbook;

            var memoryStream = new MemoryStream();

            ISheet excelSheet;

            _file?.Close();

            var bytes = new byte[0];

            _file = new FileStream(FileName, FileMode.Open, FileAccess.Read);

            {

                    _workbook = new XSSFWorkbook(_file);

                    _workbook.MissingCellPolicy = MissingCellPolicy.RETURN_NULL_AND_BLANK;

                _file.Close();

            }

            excelSheet = _workbook.GetSheetAt(0);

            IWorkbook workbook = excelSheet.Workbook;

            int i = 1;

            foreach (var member in ExcelDataObject.ListToGetColumnsData)

            {

                IRow row = excelSheet.CreateRow(i);

                row.CreateCell(0).SetCellValue(member.cell0Value);

                row.CreateCell(1).SetCellValue(member.cell2Value);

                row.CreateCell(2).SetCellValue(member.cell3Value);

               );

                i++;

            }

            using (var ms = new MemoryStream())

            {

                workbook.Write(ms, false);

                bytes = ms.ToArray();

            }

            await SaveAs(JS, FileName + ".xlsx", bytes);

        }

        async Task SaveAs(IJSRuntime js, string fileName, byte[] data)

        {

            await js.InvokeAsync<object>(

                "BlazorDownloadFile",

                fileName,

                Convert.ToBase64String(data)

            );

        }

    }

}

---------------------------------------------------------------------------------------------

Javascript Function

function BlazorDownloadFile(filename, bytesBase64) {

    var link = document.createElement('a');

    link.download = filename;

    link.href = "data:application/octet-stream;base64," + bytesBase64;

    document.body.appendChild(link); // Needed for Firefox

    link.click();

    document.body.removeChild(link);

}