High-performance CSV and XLSX exporting library for .NET 8+ built on CsvHelper and SpreadCheetah. Convention-based with fluent ExportRule API, supports async streaming, multi-sheet XLSX (1M+ rows), auto-zip for large files, column formatting, decimal precision, enum handling, and minimal API integration. Zero-config with intelligent defaults.
PandaTech.FileExporter focuses on performance, stability, and
developer happiness.
Version 5.x is a complete redesign of 4.x --- simpler, safer,
faster. API is fully modernized (minimal APIs, DI‑friendly,
async‑ready).
⚠️ Breaking Change Notice
v5 breaks compatibility with v4. Migration is straightforward: - enums
changed values --- do not reuse v4 enum values - PDF support
removed (too slow, not worth maintaining) - All exporters rebuilt
around a simpler, more predictable format system
✨ Features
Convention‑based export (zero config)\
Fluent export rules via ExportRule<T>\
Super‑fast XLSX via SpreadCheetah (safe for millions of rows)\
CSV export using CsvHelper\
Automatic ZIP compression when file size is large\
Multi‑sheet XLSX for datasets > 1M rows\
Async streaming support (IAsyncEnumerable<T>)\
Custom formatting & transforms\
Minimal API ready\
Simple DI registration\
No controllers required
🚀 Installation
dotnet add package PandaTech.FileExporter
⚙️ Quick Start
1. Configure in
Program.cs
var builder = WebApplication.CreateBuilder(args);
builder.AddFileExporter(); // scans entry assembly for ExportRule<T>
2. Export from your endpoint
app.MapGet("/export", async () =>
{
var data = new List<MyRow>
{
new() { Id = 1, Name = "Alice" },
new() { Id = 2, Name = "Bob" }
};
var file = await data.ToFileFormatAsync(ExportFormat.Xlsx);
return file.ToFileResult();
});
Done. Zero configuration required.
📄 Defining Custom Rules (Optional)
using FileExporter.Rules;
public sealed class MyRowExportRule : ExportRule<MyRow>
{
public MyRowExportRule()
{
WithName("My Custom Export");
RuleFor(x => x.Id)
.HasOrder(0)
.HasFormat(ColumnFormatType.Integer);
RuleFor(x => x.Name)
.HasOrder(1)
.WriteToColumn("Full Name");
}
}
HasPrecision(2) Decimal digit precision (not rounding, for rounding refer .Transform())
HasWidth(20) XLSX column width override
WithDefaultValue("N/A") Replaces null values
Transform(v => ...) Custom transformation
🧬 Enum Formatting
Rules support:
MixedIntAndName(default) → "1 - Active"
Int → "1"
Name → "Active"
🔥 Performance Notes
Handles millions of rows with constant memory usage\
XLSX splits automatically into multiple sheets\
ZIP is only applied when final file exceeds threshold\
Async pipelines (IAsyncEnumerable<T>) supported
🪄 Tips
Keep DTOs simple; exporters use reflection only once\
Add custom rules only for overrides --- conventions already
cover:
ordering\
decimal precision\
date formatting\
booleans\
For extremely large exports: prefer IAsyncEnumerable<T>
🧭 Demo
app.MapGet("/export/orders", async (ExportFormat format) =>
{
var orders = Enumerable.Range(1, 2000000)
.Select(i => new OrderDto { Id = i, Total = i * 1.25m });
var file = await orders.ToFileFormatAsync(format);
return file.ToFileResult();
});
Exports 2M rows in under a few seconds (depending on disk/CPU).
🏁 Conclusion
PandaTech.FileExporter is built to stay small, clean, and blazing
fast.
If you need CSV/XLSX export without pain --- you're covered.