PocketCsvReader.KeyValue 2.38.0

PocketCsvReader

PocketCsvReader is a highly efficient and lightweight library tailored for parsing delimited flat files. Optional extension packages add support for formats such as fixed-width, NDJSON, LTSV, and logfmt. With a focus on simplicity and performance, it offers seamless file reading and supports versatile outputs, including DataTables, string arrays, strongly-typed object mapping and an IDataReader interface.

About | Install | Quick-start

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Install

Replace <VersionNumber> with the desired version in each of the following solutions. If no version is specified, the latest version will be installed.

NuGet CLI

1. Open a command prompt or terminal.

2. Run the following command:

   nuget install PocketCsvReader -Version <VersionNumber>
   

Visual Studio Package Manager Console

1. Open the Package Manager Console from Tools > NuGet Package Manager > Package Manager Console.

2. Run the following command:

   Install-Package PocketCsvReader -Version <VersionNumber>
   

Dotnet-CLI

1. Open a terminal or command prompt.

2. Navigate to the directory of your project.

3. Run the following command:

   dotnet add package PocketCsvReader --version <VersionNumber>
   

   For fixed-width files, install the extension package as well:

   dotnet add package PocketCsvReader.FixedWidth --version <VersionNumber>
   

   For LTSV and logfmt records, install the key-value extension package:

   dotnet add package PocketCsvReader.KeyValue --version <VersionNumber>
   

Quick-start

The CsvReader class is a flexible and efficient tool for reading and parsing CSV files or streams into various formats, such as DataTable, IDataReader, or strongly-typed objects. This documentation explains the basics of how to use the class, including common use cases and examples.

Features

• Read CSV files or streams into a DataTable.
• Access CSV data in a forward-only, read-only manner using IDataReader.
• Map CSV records to strongly-typed objects.
• Map CSV records to array of strings.
• Customizable CSV parsing profiles for delimiters, quote handling, and more.
• Supports encoding detection through the IEncodingDetector interface.
• Read fixed-width files in one forward-only pass with field conversion deferred until a Get* accessor requests that field.
• Read labeled LTSV and logfmt records through one shared reader and format-specific builders.

Fixed-width support is distributed separately as PocketCsvReader.FixedWidth.

LTSV and logfmt support is distributed separately as PocketCsvReader.KeyValue:

using PocketCsvReader.KeyValue.Configuration;

var ltsvReader = new LtsvReaderBuilder().Build();
var logfmtReader = new LogfmtReaderBuilder().Build();

using var dataReader = logfmtReader.ToDataReader("application.log");
while (dataReader.Read())
{
    var level = dataReader.GetString(dataReader.GetOrdinal("level"));
    var message = dataReader.GetString(dataReader.GetOrdinal("message"));
}

Initialization

You can create an instance of CsvReader with various configurations:

// Default configuration: comma-delimited, double quotes for escaping, 4 KB buffer size.
var csvReader = new CsvReader();

// Custom CSV profile (e.g., semicolon-delimited, double quotes for escaping).
var csvReaderWithProfile = new CsvReader(CsvProfile.SemiColumnDoubleQuote);

// Custom buffer size for large files.
var csvReaderWithBuffer = new CsvReader(bufferSize: 64 * 1024);

// Both custom profile and buffer size.
var csvReaderCustom = new CsvReader(CsvProfile.SemiColumnDoubleQuote, bufferSize: 16 * 1024);

Reading CSV Data

Reading Into a DataTable

The ToDataTable method reads CSV data and returns a DataTable containing all rows and fields.

DataTable dataTable = csvReader.ToDataTable("example.csv");

or to read from a stream,

using var stream = new FileStream("example.csv", FileMode.Open, FileAccess.Read);
DataTable dataTable = csvReader.ToDataTable(stream);

Accessing Data with IDataReader

The ToDataReader method provides a forward-only, read-only CsvDataReader implementing IDataReader for processing large files efficiently.

using var stream = new FileStream("example.csv", FileMode.Open, FileAccess.Read);
using var reader = csvReader.ToDataReader(stream);
while (reader.Read())
{
    Console.WriteLine(reader[0]); // Access the first column of the current row.
    Console.WriteLine(reader.GetDateTime(1)); // Access the second column of the current row as an object boxing a DateTime.
    Console.WriteLine(reader.GetFieldValue<DateOnly>(2); // Access the third column of the current row as DateOnly.
}

Reading as Arrays

using var stream = new FileStream("example.csv", FileMode.Open, FileAccess.Read);
foreach (var record in csvReader.ToArrayString(stream))
{
    Console.WriteLine(string.Join(", ", record));
}

Mapping Records to Strongly-Typed Objects

The To<T> method maps CSV records to objects of a specified type.

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
}

using var stream = new FileStream("example.csv", FileMode.Open, FileAccess.Read);
IEnumerable<Person> people = csvReader.To<Person>(stream);

foreach (var person in people)
{
    Console.WriteLine($"{person.FirstName} {person.LastName}, Age: {person.Age}");
}