This is the documentation for the unsupported version 7.0. Please consider upgrading your code to the latest stable version

Inserting Data

To create or update a CSV use the following League\Csv\Writer methods.

The class has been rewritten for scalability and speed. Some previous supported features have been removed. Please refer to the upgrade section to securely migrate from previous version to 7.0 .

When creating a file using the library, first insert all the data that need to be inserted before starting manipulating the CSV. If you manipulate your data before insertion, you may change the file cursor position and get unexpected results.

Adding new data

The Writer class performs a number of actions while inserting your data into the CSV. When submitting data for insertion the class will proceed as describe below for each row.

The Writer class will:

To add new data to your CSV the Writer class uses the following methods


insertOne inserts a single row. This method can take an array, a string or an object implementing the __toString method.

class ToStringEnabledClass
    private $str;

    public function __construct($str)
        $this->str = $str;

    public function __toString()
        return $this->str;

$writer->insertOne(['john', 'doe', 'john.doe@example.com']);
$writer->insertOne(new ToStringEnabledClass("john,doe,john.doe@example.com"))


insertAll inserts multiple rows. This method can take an array or a Traversable object to add several rows to the CSV data.

$rows = [
    [1, 2, 3],
    ['foo', 'bar', 'baz'],
    new ToStringEnabledClass("john,doe,john.doe@example.com")

$writer->insertAll($rows); //using an array

$writer->insertAll(new ArrayIterator($rows)); //using a Traversable object

Row formatting

New to version 7.0

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

You can attach as many formatters as you want to the Writer class to manipulate your data prior to its insertion. The formatters follow the First In First Out rule when inserted, deleted and/or applied.

The formatter API comes with the following public API:

addFormatter(callable $callable)

Adds a formatter to the formatter collection;

removeFormatter(callable $callable)

Removes an already registered formatter. If the formatter was registered multiple times, you will have to call removeFormatter as often as the formatter was registered. The first registered copy will be the first to be removed.

hasFormatter(callable $callable)

Checks if the formatter is already registered


removes all registered formatters.

use League\Csv\Writer;

$writer->addFormatter(function ($row) {
    return array_map('strtoupper', $row);
$writer->insertOne(['john', 'doe', 'john.doe@example.com']);

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

If you are relying on the removed null handling feature the library comes bundle with the following classes to help you migrate to the new version.

Please refers to the migration guide for more information.

Row validation

New to version 7.0

A validator is a callable which takes a array as its sole argument and returns a boolean. The validator must return true to validate the submitted row. Any other expression, including truthy ones like yes, 1,… will make the insertOne method throw an League\Csv\Exception\InvalidRowException.

As with the new formatter capabilities, you can attach as many validators as you want to your data prior to its insertion. The row data is checked against your supplied validators after being formatted.

The validator API comes with the following public API:

addValidator(callable $callable, $validator_name)

Adds a validator each time it is called. The method takes two parameters:


Removes an already registered validator by using the validator registrated name


Checks if the validator is already registered


Removes all registered validators

Validation failed

If the validation failed a League\Csv\Exception\InvalidRowException is thrown by the Writer object. This exception extends PHP’s InvalidArgumentException by adding two public getter methods


returns the name of the failed validator


returns the invalid data submitted to the validator

Validation example

use League\Csv\Writer;
use League\Csv\Exception\InvalidRowException;

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

If you are relying on the removed features null handling and the column consistency, the library comes bundle with the following classes to help you migrate to the new version.

Please refers to the migration guide for more information.

Stream filtering

Some data formatting can still occur while writing the data to the CSV document after validation using the Stream Filters capabilities.

Handling newline

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

At any given time you can get and modify the $newline property using the getNewline and setNewline methods described in CSV properties documentation page.

$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";

Please refer to the BOM character dedicated documentation page for more information on how the library manage the BOM character.