DataGrid Export — Lumeo Documentation

Quick Start

IDataGridExportService is registered automatically by AddLumeo(). Inject it, describe your columns once, then call ToCsv / ToExcel / ToPdf to get the bytes, and DownloadAsync to stream them to the browser.

@inject IDataGridExportService Export

var columns = new[]
{
    new DataGridExportColumn<Order>("Id",     o => o.Id),
    new DataGridExportColumn<Order>("Date",   o => o.Date,   "yyyy-MM-dd"),
    new DataGridExportColumn<Order>("Amount", o => o.Amount, "C2"),
};

var bytes = Export.ToExcel(orders, columns, sheetName: "Orders");
await Export.DownloadAsync(bytes, "orders.xlsx",
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");

PDF export is powered by QuestPDF under its Community license. If your company has more than $1M in annual revenue you must purchase a QuestPDF Professional license and set QuestPDF.Settings.License = LicenseType.Professional; once at app startup.

Live Demo

A small product catalogue. Click any export button to download the full table.

The Export PDF button is disabled here because QuestPDF's renderer needs a native Skia dependency that isn't available under browser-wasm. CSV and Excel work on every runtime.

SKU	Name	Category	Price	Stock	Added
SKU-001	Logitech MX Master 3S	Electronics	¤99.00	42	2025-10-12
SKU-002	Herman Miller Aeron	Furniture	¤1,395.00	7	2025-11-03
SKU-003	Moleskine Classic	Stationery	¤24.50	200	2026-01-08
SKU-004	Nespresso Vertuo	Appliances	¤199.00	18	2026-02-14
SKU-005	Sony WH-1000XM5	Electronics	¤349.99	33	2026-03-22

API Reference

IDataGridExportService

Method	Returns	Description
ToCsv<T>(items, columns)	byte[]	UTF-8 CSV with BOM. Escapes commas, quotes, newlines.
ToExcel<T>(items, columns, sheetName)	byte[]	.xlsx with bolded header row, auto-fit columns, frozen first row.
ToPdf<T>(items, columns, title)	byte[]	Portrait A4 with title, timestamp and page numbers.
DownloadAsync(bytes, fileName, mimeType)	Task	Triggers a browser download via JS interop.

DataGridExportColumn<T> Record

Property	Type	Description
Header	string	Text shown in the header row for CSV / Excel / PDF.
Accessor	Func<T, object?>	Returns the raw cell value for a given row.
Format	string?	Optional format string applied to IFormattable values (e.g. "N2", "yyyy-MM-dd", "C2").

Lazy loading (Blazor WebAssembly) — since v3.7.0

The Excel (ClosedXML) and PDF (QuestPDF) backends compile into a separate Lumeo.DataGrid.Export.dll that ships inside the Lumeo.DataGrid NuGet package. On Blazor WebAssembly you can lazy-load it on demand, keeping ~1.65 MB (brotli) of dependencies out of the initial download. Server scenarios are unaffected — the backend always loads eagerly there.

1. Mark the assemblies lazy

In your WASM app's .csproj:

<ItemGroup>
  <BlazorWebAssemblyLazyLoad Include="Lumeo.DataGrid.Export.dll" />
  <BlazorWebAssemblyLazyLoad Include="ClosedXML.dll" />
  <BlazorWebAssemblyLazyLoad Include="ClosedXML.Parser.dll" />
  <BlazorWebAssemblyLazyLoad Include="DocumentFormat.OpenXml.dll" />
  <BlazorWebAssemblyLazyLoad Include="DocumentFormat.OpenXml.Framework.dll" />
  <BlazorWebAssemblyLazyLoad Include="ExcelNumberFormat.dll" />
  <BlazorWebAssemblyLazyLoad Include="RBush.dll" />
  <BlazorWebAssemblyLazyLoad Include="SixLabors.Fonts.dll" />
  <BlazorWebAssemblyLazyLoad Include="System.IO.Packaging.dll" />
  <BlazorWebAssemblyLazyLoad Include="QuestPDF.dll" />
</ItemGroup>

2. Wire the loader hook

In Program.cs:

using Lumeo.Services;
using Microsoft.AspNetCore.Components.WebAssembly.Services;

var host = builder.Build();
var lazy = host.Services.GetRequiredService<LazyAssemblyLoader>();
DataGridExportLoader.LoadAssembliesAsync = names => lazy.LoadAssembliesAsync(names);
await host.RunAsync();

The DataGrid component awaits the loader before its toolbar export, so Excel pulls the ClosedXML closure and PDF pulls QuestPDF on the first click — an Excel-only WASM user never downloads QuestPDF. If you call IDataGridExportService.ToExcel/ToPdf directly (not via the DataGrid toolbar), first await DataGridExportLoader.EnsureExcelAssembliesAsync() / EnsurePdfAssembliesAsync() — the synchronous service methods can't fetch a lazy assembly themselves. Without this opt-in nothing breaks: the backend loads eagerly at startup like before.

3. Direct service calls (optional)

When calling the service yourself on a lazy-loading WASM app, preload first:

await DataGridExportLoader.EnsureExcelAssembliesAsync();
var bytes = Export.ToExcel(rows, columns, sheetName: "Data");
await Export.DownloadAsync(bytes, "data.xlsx",
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");