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[UID] Added the docs for the component #13338

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187 changes: 187 additions & 0 deletions components/uid.rst
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.. index::
single: UID
single: Components; UID

The UID Component
=================

The UID component provides utilities to work with `unique identifiers`_ (UIDs)
such as UUIDs and ULIDs.

.. versionadded:: 5.1

The UID component was introduced in Symfony 5.1 as an
:doc:`experimental feature </contributing/code/experimental>`.

Installation
------------

.. code-block:: terminal

$ composer require symfony/uid

.. include:: /components/require_autoload.rst.inc

UUIDs
-----

`UUIDs`_ (*universally unique identifiers*) are one of the most popular UIDs in
the software industry. UUIDs are 128-bit numbers usually represented as five
groups of hexadecimal characters: ``xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx``
(the ``M`` digit is the UUID version and the ``N`` digit is the UUID variant).

Generating UUIDs
~~~~~~~~~~~~~~~~

Use the named constructors of the ``Uuid`` class or any of the specific classes
to create each type of UUID::

use Symfony\Component\Uid\Uuid;

// UUID type 1 generates the UUID using the MAC address of your device and a timestamp.
// Both are obtained automatically, so you don't have to pass any constructor argument.
$uuid = Uuid::v1(); // $uuid is an instance of Symfony\Component\Uid\UuidV1

// UUID type 4 generates a random UUID, so you don't have to pass any constructor argument.
$uuid = Uuid::v4(); // $uuid is an instance of Symfony\Component\Uid\UuidV4

// UUID type 3 and 5 generate a UUID hashing the given namespace and name. Type 3 uses
// MD5 hashes and Type 5 uses SHA-1. The namespace is another UUID (e.g. a Type 4 UUID)
// and the name is an arbitrary string (e.g. a product name; if it's unique).
$namespace = Uuid::v4();
$name = $product->getUniqueName();

$uuid = Uuid::v3($namespace, $name); // $uuid is an instance of Symfony\Component\Uid\UuidV3
$uuid = Uuid::v5($namespace, $name); // $uuid is an instance of Symfony\Component\Uid\UuidV5

// UUID type 6 is not part of the UUID standard. It's lexicographically sortable
// (like ULIDs) and contains a 60-bit timestamp and 63 extra unique bits.
// It's defined in http://gh.peabody.io/uuidv6/
$uuid = Uuid::v6(); // $uuid is an instance of Symfony\Component\Uid\UuidV6

If your UUID is generated by another system, use the ``fromString()`` method to
create an object and make use of the utilities available for Symfony UUIDs::

// this value is generated somewhere else
$uuidValue = 'd9e7a184-5d5b-11ea-a62a-3499710062d0';
$uuid = Uuid::fromString($uuidValue);

If your UUIDs are generated in binary format, use the ``fromBinary()`` method
to create the objects for them::

$uuid = Uuid::fromBinary($uuidBinaryContents);

Converting UUIDs
~~~~~~~~~~~~~~~~

Use these methods to transform the UUID object into different bases::

$uuid = new Uuid::fromString('d9e7a184-5d5b-11ea-a62a-3499710062d0');

$uuid->toBinary(); // string(16) "..." (binary contents can't be printed)
$uuid->toBase32(); // string(26) "6SWYGR8QAV27NACAHMK5RG0RPG"
$uuid->toBase58(); // string(22) "TuetYWNHhmuSQ3xPoVLv9M"
$uuid->toRfc4122(); // string(36) "d9e7a184-5d5b-11ea-a62a-3499710062d0"

Working with UUIDs
~~~~~~~~~~~~~~~~~~

UUID objects created with the ``Uuid`` class can use the following methods
(which are equivalent to the ``uuid_*()`` method of the PHP extension)::

use Symfony\Component\Uid\NilUuid;
use Symfony\Component\Uid\Uuid;

// checking if the UUID is null (note that the class is called
// NilUuid instead of NullUuid to follow the UUID standard notation)
$uuid = Uuid::v4();
$uuid instanceof NilUuid; // false

// checking the type of UUID
use Symfony\Component\Uid\UuidV4;
$uuid = Uuid::v4();
$uuid instanceof UuidV4; // true

// getting the UUID time (it's only available in certain UUID types)
$uuid = Uuid::v1();
$uuid->getTime(); // e.g. float(1584111384.2613)

// comparing UUIDs and checking for equality
$uuid1 = Uuid::v1();
$uuid4 = Uuid::v4();
$uuid1->equals($uuid4); // false

// this method returns:
// * int(0) if $uuid1 and $uuid4 are equal
// * int > 0 if $uuid1 is greater than $uuid4
// * int < 0 if $uuid1 is less than $uuid4
$uuid1->compare($uuid4); // e.g. int(4)

ULIDs
-----

`ULIDs`_ (*Universally Unique Lexicographically Sortable Identifier*) are 128-bit
numbers usually represented as a 26-character string: ``TTTTTTTTTTRRRRRRRRRRRRRRRR``
(where ``T`` represents a timestamp and ``R`` represents the random bits).

ULIDs are an alternative to UUIDs when using those is impractical. They provide
128-bit compatibility with UUID, they are lexicographically sortable and they
are encoded as 26-character strings (vs 36-character UUIDs).

Generating ULIDs
~~~~~~~~~~~~~~~~

Instantiate the ``Ulid`` class to generate a random ULID value::

use Symfony\Component\Uid\Ulid;

$ulid = new Ulid(); // e.g. 01AN4Z07BY79KA1307SR9X4MV3

If your UUID is generated by another system, use the ``fromString()`` method to
create an object and make use of the utilities available for Symfony ULIDs::

// this value is generated somewhere else
$ulidValue = '01E439TP9XJZ9RPFH3T1PYBCR8';
$ulid = Ulid::fromString($ulidValue);

If your ULIDs are generated in binary format, use the ``fromBinary()`` method
to create the objects for them::

$ulid = Ulid::fromBinary($ulidBinaryContents);

Converting ULIDs
~~~~~~~~~~~~~~~~

Use these methods to transform the ULID object into different bases::

$ulid = Ulid::fromString('01E439TP9XJZ9RPFH3T1PYBCR8');

$ulid->toBinary(); // string(16) "..." (binary contents can't be printed)
$ulid->toBase32(); // string(26) "01E439TP9XJZ9RPFH3T1PYBCR8"
$ulid->toBase58(); // string(22) "1BKocMc5BnrVcuq2ti4Eqm"
$ulid->toRfc4122(); // string(36) "0171069d-593d-97d3-8b3e-23d06de5b308"

Working with ULIDs
~~~~~~~~~~~~~~~~~~

ULID objects created with the ``Ulid`` class can use the following methods::

use Symfony\Component\Uid\Ulid;

$ulid1 = new Ulid();
$ulid2 = new Ulid();

// checking if a given value is valid as ULID
$isValid = Ulid::isValid($ulidValue); // true or false

// getting the ULID time
$ulid1->getTime(); // e.g. float(1584111384.2613)

// comparing ULIDs and checking for equality
$ulid1->equals($ulid2); // false
// this method returns $ulid1 <=> $ulid2
$uuid1->compare($uuid4); // e.g. int(-1)

.. _`unique identifiers`: https://en.wikipedia.org/wiki/UID
.. _`UUIDs`: https://en.wikipedia.org/wiki/Universally_unique_identifier
.. _`ULIDs`: https://github.com/ulid/spec