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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

$ composer require symfony/uid

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 ULID 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
$ulid1->compare($ulid2); // e.g. int(-1)