The League of Extraordinary Packages

Our Packages:

Presented by The League of Extraordinary Packages

Getting Started

Connections Settings

Inserting Records

Selecting Records


Converting Records

Upgrading Guide

This is the documentation for the upcoming version 9.0. This is a work in progress

Writer connection


class Writer extends AbstractCsv
    public function addFormatter(callable $callable): Writer
    public function addValidator(callable $callable, string $validatorName): Writer
    public function getFlushThreshold(): int|null
    public function getNewline(): string
    public function insertAll(iterable $records): int
    public function insertOne(array $record): int
    public function setFlushThreshold(?int $threshold): self
    public function setNewline(string $sequence): self

The League\Csv\Writer class extends the general connections capabilities to create or update a CSV document.

When inserting records into a CSV document using League\Csv\Writer, first insert all the data that need to be inserted before starting manipulating the CSV. If you manipulate your CSV document before insertion, you may change the file cursor position and/or erased your data.

Inserting records


public Writer::insertOne(array $record): int
public Writer::insertAll(iterable $records): int

Writer::insertOne inserts a single record into the CSV document while Writer::insertAll adds several records. Both methods returns the length of the written data or throw and League\Csv\Exception\InsertionException on error.

Writer::insertOne takes a single argument, an array which represents a single CSV record. Writer::insertAll takes a single argument a PHP iterable which contains a collection of CSV records.


use League\Csv\Writer;

$records = [
    [1, 2, 3],
    ['foo', 'bar', 'baz'],
    ['john', 'doe', ''],

$writer = Writer::createFromPath('/path/to/saved/file.csv', 'w+');
$writer->insertOne(['john', 'doe', '']);
$writer->insertAll($records); //using an array
$writer->insertAll(new ArrayIterator($records)); //using a Traversable object

In the above example, all CSV records are saved to /path/to/saved/file.csv

Handling newline

Because PHP’s fputcsv implementation has a hardcoded \n, we need to be able to replace the last LF code with one supplied by the developper for more interoperability between CSV packages on different platforms. The newline sequence will be appended to each newly inserted CSV record.



public Writer::setNewline(string $sequence): self
public Writer::getNewline(void): string



use League\Csv\Writer;

$writer = Writer::createFromFileObject(new SplFileObject());
$newline = $writer->getNewline(); // equals "\n";
$newline = $writer->getNewline(); // equals "\r\n";
$writer->insertOne(["one", "two"]);
echo $writer; // displays "one,two\r\n";

The default newline sequence is \n;

Flushing the buffer

For advanced usages, you can now manually indicates when flushing mechanism occurs while adding new content to your CSV document.



public Writer::setFlushThreshold(?int $treshold): self
public Writer::getFlushThreshold(void): int|null

By default, getFlushTreshold returns null.

Writer::insertAll always flush its buffer when all records are inserted regardless of the threshold value.

If set to null the inner flush mechanism of SplFileObject::fputcsv or fputcsv will be used.

Records filtering


public Writer::addFormatter(callable $callable): Writer
public Writer::addValidator(callable $callable, string $validatorName): Writer

Sometimes you may want to format and/or validate your records prior to their insertion into your CSV document. the Writer class provides a formatter and a validator mechanism to ease these operations.

Record Formatter

A formatter is a callable which accepts an array on input and returns a formatted array according to its inner rules.


function(array $record): array

You can attach as many formatters as you want to the Writer class to manipulate your data prior to its insertion use the Writer::addFormatter method. The formatters follow the First In First Out rule when applied.


use League\Csv\Writer;

$formatter = function (array $row): array {
    return array_map('strtoupper', $row);
$writer = Writer::createFromFileObject(new SplTempFileObject());
$writer->insertOne(['john', 'doe', '']);

//will display something like JOHN,DOE,JOHN.DOE@EXAMPLE.COM

Record Validator

A validator is a callable which takes an array as its sole argument and returns a boolean.


function(array $record): bool

The validator must return true to validate the submitted record.

Any other expression, including thruthy ones like yes, 1,… will make the insertOne method throw an League\Csv\Exception\InsertionException.

As with the formatter capabilities, you can attach as many validators as you want to your data prior to its insertion using the Writer::addValidator method. The record data is checked against your supplied validators after it has been formatted.

Writer::addValidator takes two parameters:

On failure a League\Csv\Exception\InsertionException exception is thrown by the Writer object.


use League\Csv\Writer;
use League\Csv\Exception\InsertionException;

$writer->addValidator(function (array $row): bool {
    return 10 == count($row);
}, 'row_must_contain_10_cells');
try {
    $writer->insertOne(['john', 'doe', '']);
} catch (InsertionException $e) {
    echo $e->getName(); //display 'row_must_contain_10_cells'
    $e->getData();//will return the invalid data ['john', 'doe', '']