arjunvachhani / xlsxhelper

An memory efficient, fast excel file reader designed for processing large Xlsx files.

XlsxHelper

XlsxHelper has been crafted with the primary intention of efficiently parsing extensive Excel files. This library is designed to be lightweight, ensuring that it doesn't load the entire dataset into memory all at once. Instead, it adopts a sequential approach, fetching and returning one row per iteration. As a result of this methodology, the memory overhead is minimized.

When to use XlsxHelper

• You need to process large xlsx file.
• You want to read content with very little RAM usage.
• You want full control of mapping/parsing fields to Model.

When to not use XlsxHelper

• You want to read rows in random manner.
• You want to read thing like width of row/column, font size / color etc
• You want to read xls file format.

Project Status

XlsxHelper is actively maintained. Please feel free to ask question and raise issues.

How to get started

Install NuGet package https://www.nuget.org/packages/XlsxHelper/

Example 1

using (var workbook = XlsxReader.OpenWorkbook(filePath))
{
    foreach (var worksheet in workbook.Worksheets)//read all worksheets
    {
        Console.WriteLine($"Worksheet {worksheet.Name}"); //get name of worksheet
        using var worksheetReader = worksheet.WorksheetReader; //get WorksheetReader from worksheet
        foreach (var row in worksheetReader) //read row from worksheetreader
        {
            Console.WriteLine($"Content of row {row.RowNumber}"); //display current row number
            foreach (var cell in row.Cells) // Display all cell content
            {
                Console.WriteLine($"[{cell.CellValue} at ({cell.ColumnName}{row.RowNumber})]");
            }
            Console.WriteLine($"Content of row {row.RowNumber} ends.");
        }
    }
}

Example 2

using (var workbook = XlsxReader.OpenWorkbook(filePath))
{
    var worksheet = workbook.Worksheets.First();
    bool headerRow = true;
    Dictionary<string, ColumnName> headerLooklup = null;
    foreach (var row in worksheet.WorksheetReader)
    {
        if (headerRow)
        {
            headerLooklup = ReadHeader(row); //Read all header names from first row
            headerRow = false;
            continue;
        }
        var student = new Student();
        student.FirstName = row[headerLooklup[nameof(Student.FirstName)]].CellValue; //get cell value 
        student.LastName = row[headerLooklup[nameof(Student.LastName)]].CellValue;
        student.Grade = row[headerLooklup[nameof(student.Grade)]].CellValue;
        student.Marks = new Marks
        {
            Biology = row[headerLooklup[nameof(Marks.Biology)]].GetInt32(),
            Chemistry = row[headerLooklup[nameof(Marks.Chemistry)]].GetInt32(),
            Mathematics = row[headerLooklup[nameof(Marks.Mathematics)]].GetInt32(),
            Physics = row[headerLooklup[nameof(Marks.Physics)]].GetInt32()
        };

        //Process student object. 
        //yield return student;
    }

    static Dictionary<string, ColumnName> ReadHeader(Row row) //read header
    {
        Dictionary<string, ColumnName> headerLooklup = new Dictionary<string, ColumnName>();
        foreach (var cell in row.Cells)
        {
            headerLooklup.Add(cell.CellValue, cell.ColumnName);
        }
        return headerLooklup;
    }
}

XlsxHelper is fast and lightweight for normal files. Below results shows time and memory used to read 50MB/50,000 Records

	XlsxHelper	LightweightExcelReader	ExcelDataReader AsDataset	ExcelDataReader
Time to read first row	5ms	14ms	-	-
Time to read all rows(50,000)	3.90 sec	7.60 sec	13.50 sec	10.10 sec
Memory usage at the time of reading first row	31.412 MB	32.649 MB	-	42.057 MB
Memory usage at the time of reading last row	38.891 MB	901.976 MB	471.662 MB	42.414 MB

XlsxHelper is memory optimized for reading huge xlsx files. see below results for reading 1 Million Employee records

	XlsxHelper	ExcelDataReader
Time to read first row	5ms	-
Time to read all rows(1,000,000)	102.50 sec	61.10 sec
Memory usage at the time of reading first row	31.920 MB	668.381 MB
Memory usage at the time of reading last row	41.103 MB	667.934 MB