SpreadSheetTasks 1.0.0

SpreadSheetTasks

The .NET library for fast reading and writing Excel files (.xlsx, .xlsb).

Installation

dotnet add package SpreadSheetTasks

<PackageReference Include="SpreadSheetTasks" Version="1.0.0" />

Quick Start

Write to Excel

using SpreadSheetTasks;
using System.Data;

var dt = new DataTable();
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Age", typeof(int));
dt.Rows.Add("Alice", 30);
dt.Rows.Add("Bob", 25);

using (var writer = new XlsxWriter("output.xlsx")) // or XlsbWriter
{
    writer.AddSheet("People");
    writer.WriteSheet(dt.CreateDataReader());
}

Read from Excel

using SpreadSheetTasks;

using (var reader = new XlsxOrXlsbReadOrEdit())
{
    reader.Open("output.xlsx");
    reader.ActualSheetName = "People";

    object[]? row = null;
    while (reader.Read())
    {
        row ??= new object[reader.FieldCount];
        reader.GetValues(row);
    }
}

Documentation

Full usage guide with detailed examples:

• docs/index.md

Write from object[][] (typed headers)

using SpreadSheetTasks;

using (var writer = new XlsxWriter("products.xlsx"))
{
    writer.AddSheet("Products");
    writer.WriteSheet(
        rows: new object[][]
        {
            new object[] { "Apple", 1.99, 100 },
            new object[] { "Banana", 0.99, 250 },
        },
        headers: new[] { "Product", "Price", "Quantity" },
        headers_row: true,
        doAutofilter: true
    );
}

Write with per-cell formatting (FormattedCell[][])

using SpreadSheetTasks;

using (var writer = new XlsxWriter("formatted.xlsx"))
{
    writer.AddSheet("Sheet1");
    writer.WriteSheet(
        rows: new object[][]
        {
            new object[] { 1234567, 1234.56 },
            new object[] { 0.25, 12345.67 },
        },
        headers: new[] { "Thousands", "Scientific" },
        formats: new FormattedCell[][]
        {
            new FormattedCell[] { new(1234567, F.THOUSANDS_SEP), new(1234.56, F.CURRENCY_PLN) },
            new FormattedCell[] { new(0.25, F.PERCENTAGE), new(12345.67, F.SCIENTIFIC) },
        }
    );
}

GetExcelDataType / GetNativeValue

using SpreadSheetTasks;

using (var reader = new XlsxOrXlsbReadOrEdit())
{
    reader.Open("data.xlsx");
    reader.ActualSheetName = "Sheet1";

    while (reader.Read())
    {
        // Use typed getters for general use
        string name = reader.GetString(0);
        long value = reader.GetInt64(1);

        // Use GetExcelDataType to inspect cell type
        ExcelDataType type = reader.GetExcelDataType(2);

        // High-performance escape hatch (check type first!)
        if (type == ExcelDataType.Double)
        {
            double raw = reader.GetNativeValue(2).doubleValue;
        }
    }
}

Update existing XLSX (ReplaceSheetData + ReplacePivotTableDim)

using SpreadSheetTasks;
using System.Data;

using (var reader = new XlsxOrXlsbReadOrEdit())
{
    reader.Open("existing.xlsx", updateMode: true);

    var newData = new DataTable();
    newData.Columns.Add("Product", typeof(string));
    newData.Columns.Add("Revenue", typeof(decimal));
    newData.Rows.Add("Widget", 50000m);

    // Replace data in a sheet
    string range = reader.ReplaceSheetData("Sheet1", newData.CreateDataReader());

    // Update pivot table data source reference
    reader.ReplacePivotTableDim("PivotTable1", range);
}

Write to existing Stream (XlsxWriter.WriteToExisting)

using SpreadSheetTasks;
using System.Data;
using System.IO;
using System.IO.Compression;

// Open an existing xlsx as a ZipArchive and write into a sheet stream
using (var archive = ZipFile.Open("existing.xlsx", ZipArchiveMode.Update))
{
    var entry = archive.GetEntry("xl/worksheets/sheet1.xml");
    using var writer = new StreamWriter(entry.Open());

    var dt = new DataTable();
    dt.Columns.Add("Name", typeof(string));
    dt.Rows.Add("Alice");

    int rowsWritten = XlsxWriter.WriteToExisting(writer, dt.CreateDataReader());
}

Stream writer with custom buffer size

using SpreadSheetTasks;
using System.Data;

// Larger buffer for better write throughput on large files
using (var writer = new XlsxWriter("large.xlsx", bufferSize: 65536))
{
    writer.AddSheet("Data");
    var dt = new DataTable();
    dt.Columns.Add("Col", typeof(string));
    for (int i = 0; i < 100_000; i++) dt.Rows.Add($"Row{i}");
    writer.WriteSheet(dt.CreateDataReader());
}

Breaking Changes in v1.0.0

Old names still compile with [Obsolete] warnings.

Benchmarks

Tested on: Windows 11, AMD Ryzen 7 7840HS, .NET 10.0.8 (10.0.8)

XLSB Read (65k rows)

XLSX Read (65k rows, typed getters)

XLSB Write (50k rows, mixed types)

XLSX Write (50k rows, mixed types)

Links

• NuGet: https://www.nuget.org/packages/SpreadSheetTasks/
• GitHub: https://github.com/KrzysztofDusko/SpreadSheetTasks
• License: MIT