Export grid to Excel, Pdf and txt (csv)

@{
    var grid = "LunchGrid";
}
@(Html.Awe().Grid(grid)
        .Url(Url.Action("GetItems"))
        .Mod(o => o.ColumnsSelector())
        .Persistence(Persistence.Session)
        .Resizable()
        .Height(350)
        .Columns(
        new Column { Bind = "Id", Width = 80 },
        new Column { Bind = "Person" },
        new Column { Bind = "Food.Name" },
        new Column { Bind = "Date", Width = 150 },
        new Column { Bind = "Price", ClientFormatFunc = "priceFormat", Width = 110 },
        new Column { Bind = "Country.Name", Header = "Country" },
        new Column { Bind = "Chef.FirstName,Chef.LastName", Prop = "ChefName", Header = "Chef" },
        new Column { Bind = "Location" }))

<br />
<div class="btn-cont">
    <button id="exportGrid" type="button" class="awe-btn">Export grid to excel</button>
    <button id="exportGridPdf" type="button" class="awe-btn">Export grid to Pdf</button>
    <button id="exportGridTxt" type="button" class="awe-btn">Export grid to txt (csv)</button>
    <button id="exportAll" type="button" class="awe-btn">Export all records to excel</button>        
</div>
<div class="btn-cont">
    <label>@Html.Awe().CheckBox("allPages") All pages</label>
    <label>@Html.Awe().CheckBox("loadDelay") Load delay (3 seconds)</label>
</div>
<script>
    $(function() {
        $('#exportAll').click(function() {
            getFile('@Url.Action("ExportAllToExcel", "GridExportToExcelDemo")');
        });

        $('#exportGrid').click(function() {
            getFile('@Url.Action("ExportGridToExcel", "GridExportToExcelDemo")');
        });

        $('#exportGridPdf').click(function() {
            getFile('@Url.Action("ExportGridToPdf", "GridExportToExcelDemo")');
        });

        $('#exportGridTxt').click(function() {
            getFile('@Url.Action("ExportGridToTxt", "GridExportToExcelDemo")');
        });
    });

    async function getFile(url) {
        // Collect request parameters from the grid
        var grid = $('#@(grid)');
        var req = grid.data('api').getRequest();
        
        var expCols = getExpColumns(grid);
        
        var formData = new FormData();

        // Add visible columns info
        expCols.forEach((col, i) => {
            formData.append(`expColumns[${i}].Name`, col.name);
            formData.append(`expColumns[${i}].Header`, col.header);
            formData.append(`expColumns[${i}].Width`, col.width);
            formData.append(`expColumns[${i}].Hidden`, col.hidden);
        });

        // Add request parameters
        req.forEach(val => {
            formData.append(val.name, val.value);
        });                
        
        formData.append('allPages', $('#allPages').val());
        formData.append('loadDelay', $('#loadDelay').val());

        try {
            const loadAnim = awem.loadingAnim({ cont: $('body') });
            loadAnim.start();

            // Make POST request using fetch
            let response = await fetch(url, {
                method: "POST",
                body: formData
            });

            if (!response.ok) {
                throw new Error(`Server returned ${response.status} ${response.statusText}`);
            }

            // Extract filename from Content-Disposition header
            const contentDisposition = response.headers.get("Content-Disposition");            
            let filename = contentDisposition.match(/filename=([^;]+)/)?.[1].trim() || 'download.xls';

            let blob = await response.blob();
            loadAnim.stop();

            // Trigger file download
            const downloadUrl = window.URL.createObjectURL(blob);
            const a = document.createElement("a");
            a.href = downloadUrl;
            a.download = filename;
            document.body.appendChild(a);
            a.click();
            a.remove();
            window.URL.revokeObjectURL(downloadUrl);

        } catch (error) {
            loadAnim.stop();
            console.error("Download failed:", error);
        }
    }

    function getExpColumns(g) {
        return awef.select(g.data('o').columns,
            function (col) {
                return { name: col.T || col.P, header: col.Header, hidden: !!col.Hid, width: col.W || col.Mw || col.needw };
            });
    }

    function priceFormat(lunch, prop) {
        var price = lunch[prop];
        return price + ' USD';
    }
</script>

public class GridExportToExcelDemoController : Controller
{
    public IActionResult Index()
    {
        return View();
    }

    public IActionResult GetItems(GridParams g)
    {
        return Json((BuildGridModel(g)).ToDto());
    }

    private GridModel<Lunch> BuildGridModel(GridParams g)
    {
        var query = Db.Lunches.AsQueryable();

        var gmb = new GridModelBuilder<Lunch>(query, g)
        {
            KeyProp = o => o.Id,
            Map = o => new
            {
                o.Id,
                o.Person,
                FoodName = o.Food.Name,
                o.Location,
                o.Price,
                Date = o.Date.ToShortDateString(),
                CountryName = o.Country.Name,
                ChefName = o.Chef.FullName
            },
            MakeFooter = info =>
                {
                    if (info.Level == 0)
                    {
                        return new
                        {
                            Id = "Total",
                            Price = "Min: " + info.Items.Min(o => o.Price),
                            Date = "Max: " + info.Items.Max(o => o.Date).ToShortDateString()
                        };
                    }

                    return new
                    {
                        Price = "Min: " + info.Items.Min(o => o.Price),
                        Date = "Max: " + info.Items.Max(o => o.Date).ToShortDateString()
                    };
                }
        };

        return gmb.BuildModel();
    }

    private IEnumerable<ExpColumn> addServerFormatting(IEnumerable<ExpColumn> columns)
    {
        var priceColumn = columns.SingleOrDefault(o => o.Name == "Price");

        if (priceColumn != null)
        {
            priceColumn.ClientFormatFunc = (lunch, property) =>
            {
                var value = lunch.GetType().GetProperty("Price")?.GetValue(lunch).ToString();
                if (!string.IsNullOrEmpty(value))
                {
                    value += " USD";
                }

                return value;
            };

            priceColumn.Width = 200;
        }

        return columns;
    }

    [HttpPost]
    public async Task<IActionResult> ExportGridToExcel(
        GridParams g, 
        IEnumerable<ExpColumn> expColumns, 
        bool? allPages,
        bool? loadDelay)
    {
        if (loadDelay == true)
        {
            await Task.Delay(3000);
        }            

        if (allPages.HasValue && allPages.Value)
        {
            g.Paging = false;
        }

        var gridModel = BuildGridModel(g);

        var workbook = new GridExcelBuilder(expColumns.Where(o => !o.Hidden)).Build(gridModel);

        using (var stream = new MemoryStream())
        {
            workbook.Write(stream);
            stream.Close();
            return File(stream.ToArray(), "application/vnd.ms-excel", "lunches.xls");
        }
    }

    [HttpPost]
    public async Task<IActionResult> ExportGridToTxt(
        GridParams g, 
        IEnumerable<ExpColumn> expColumns, 
        bool? allPages,
        bool? loadDelay)
    {
        if (loadDelay == true)
        {
            await Task.Delay(3000);
        }

        if (allPages.HasValue && allPages.Value)
        {
            g.Paging = false;
        }

        var gridModel = BuildGridModel(g);

        var res = new GridTxtBuilder(expColumns.Where(o => !o.Hidden)).Build(gridModel);

        using (var memoryStream = new MemoryStream())
        {
            using (var writer = new StreamWriter(memoryStream))
            {
                writer.WriteLine(res);
            }

            return File(memoryStream.ToArray(), "text/plain", "lunches.txt");
        }
    }

    [HttpPost]
    public async Task<IActionResult> ExportGridToPdf(
        GridParams g, 
        IEnumerable<ExpColumn> expColumns, 
        bool? allPages, 
        bool? loadDelay)
    {
        if (loadDelay == true)
        {
            await Task.Delay(3000);
        }

        if (allPages.HasValue && allPages.Value)
        {
            g.Paging = false;
        }

        var gridModel = BuildGridModel(g);

        var builder = new GridPdfBuilder(addServerFormatting(expColumns.Where(o => !o.Hidden)));

        var workStream = new MemoryStream();
        var writer = new PdfWriter(workStream);
        var pdf = new PdfDocument(writer);
        var document = new Document(pdf);

        document.Add(new Paragraph("Hello World!"));
        document.Add(new Paragraph("Export to pdf example (using iText7)"));
        document.Add(new Paragraph(new Text("\n")));

        var table = builder.Build(gridModel);
        document.Add(table);
        writer.SetCloseStream(false);
        document.Close();

        var byteInfo = workStream.ToArray();
        workStream.Write(byteInfo, 0, byteInfo.Length);
        workStream.Position = 0;

        return File(workStream, "application/pdf", "lunches.pdf");
    }

    /// <summary>
    /// Demonstrates the simplest way of creating an excel workbook 
    /// it exports all the lunches records, without taking into account any sorting/paging that is done on the client side
    /// </summary>
    /// <returns></returns>
    [HttpPost]
    public async Task<IActionResult> ExportAllToExcel(bool? loadDelay)
    {
        if (loadDelay == true)
        {
            await Task.Delay(3000);
        }

        var workbook = new HSSFWorkbook();
        var sheet = workbook.CreateSheet("sheet1");

        var res = Db.Lunches.ToArray();

        var items = res.Select(
            o => new
            {
                o.Id,
                o.Person,
                FoodName = o.Food.Name,
                o.Location,
                CountryName = o.Country.Name,
                ChefName = o.Chef.FullName
            }).ToList();

        var properties = new[] { "Id", "Person", "FoodName", "CountryName", "ChefName", "Location" };
        var headers = new[] { "Id", "Person", "Food", "Country", "Chef", "Location" };

        var headerRow = sheet.CreateRow(0);

        // create header
        for (int i = 0; i < properties.Length; i++)
        {
            var cell = headerRow.CreateCell(i);
            cell.SetCellValue(headers[i]);
        }

        // fill content 
        for (int i = 0; i < items.Count; i++)
        {
            var rowIndex = i + 1;
            var row = sheet.CreateRow(rowIndex);

            for (int j = 0; j < properties.Length; j++)
            {
                var cell = row.CreateCell(j);
                var o = items[i];
                cell.SetCellValue(o.GetType().GetProperty(properties[j]).GetValue(o, null).ToString());
            }
        }

        using (var stream = new MemoryStream())
        {
            workbook.Write(stream);
            stream.Close();
            return File(stream.ToArray(), "application/vnd.ms-excel", "lunches.xls");
        }
    }
}