The UID Component

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The UID Component

The UID Component¶

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

New in version 5.1: The UID component was introduced in Symfony 5.1.

Installation¶

1	$ composer require symfony/uid

Note

If you install this component outside of a Symfony application, you must require the vendor/autoload.php file in your code to enable the class autoloading mechanism provided by Composer. Read this article for more details.

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

// the namespaces defined by RFC 4122 are available as constants
// (see https://tools.ietf.org/html/rfc4122#appendix-C)
$uuid = Uuid::v3(Uuid::NAMESPACE_DNS, $name);
$uuid = Uuid::v3(Uuid::NAMESPACE_URL, $name);
$uuid = Uuid::v3(Uuid::NAMESPACE_OID, $name);
$uuid = Uuid::v3(Uuid::NAMESPACE_X500, $name);

// 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

New in version 5.3: The Uuid::NAMESPACE_* constants were introduced in Symfony 5.3.

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 (can also be in binary format)
$uuidValue = 'd9e7a184-5d5b-11ea-a62a-3499710062d0';
$uuid = Uuid::fromString($uuidValue);

Converting UUIDs¶

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

$uuid = 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 datetime (it's only available in certain UUID types)
$uuid = Uuid::v1();
$uuid->getDateTime();  // returns a \DateTimeImmutable instance

// 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)

New in version 5.3: The getDateTime() method was introduced in Symfony 5.3. In previous versions it was called getTime().

Storing UUIDs in Databases¶

If you use Doctrine, consider using the uuid Doctrine type, which converts to/from UUID objects automatically:

// src/Entity/Product.php
namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ProductRepository")
 */
class Product
{
    /**
     * @ORM\Column(type="uuid")
     */
    private $someProperty;

    // ...
}

New in version 5.2: The UUID type was introduced in Symfony 5.2.

There is no generator to assign UUIDs automatically as the value of your entity primary keys, but you can use the following:

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Uid\Uuid;
// ...

class User implements UserInterface
{
    /**
     * @ORM\Id
     * @ORM\Column(type="uuid", unique=true)
     */
    private $id;

    public function __construct()
    {
        $this->id = Uuid::v4();
    }

    public function getId(): Uuid
    {
        return $this->id;
    }

    // ...
}

When using built-in Doctrine repository methods (e.g. findOneBy()), Doctrine knows how to convert these UUID types to build the SQL query (e.g. ->findOneBy(['user' => $user->getUuid()])). However, when using DQL queries or building the query yourself, you’ll need to set uuid as the type of the UUID parameters:

// src/Repository/ProductRepository.php

// ...
class ProductRepository extends ServiceEntityRepository
{
    // ...

    public function findUserProducts(User $user): array
    {
        $qb = $this->createQueryBuilder('p')
            // ...
            // add 'uuid' as the third argument to tell Doctrine that this is an UUID
            ->setParameter('user', $user->getUuid(), 'uuid')

            // alternatively, you can convert it to a value compatible with
            // the type inferred by Doctrine
            ->setParameter('user', $user->getUuid()->toBinary())
        ;

        // ...
    }
}

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 (can also be in binary format)
$ulidValue = '01E439TP9XJZ9RPFH3T1PYBCR8';
$ulid = Ulid::fromString($ulidValue);

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 datetime
$ulid1->getDateTime(); // returns a \DateTimeImmutable instance

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

New in version 5.3: The getDateTime() method was introduced in Symfony 5.3. In previous versions it was called getTime().

Storing ULIDs in Databases¶

If you use Doctrine, consider using the ulid Doctrine type, which converts to/from ULID objects automatically:

// src/Entity/Product.php
namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ProductRepository")
 */
class Product
{
    /**
     * @ORM\Column(type="ulid")
     */
    private $someProperty;

    // ...
}

There’s also a Doctrine generator to help autogenerate ULID values for the entity primary keys:

use Symfony\Bridge\Doctrine\IdGenerator\UlidGenerator;
use Symfony\Component\Uid\Ulid;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ProductRepository")
 */
class Product
{
    /**
     * @ORM\Id
     * @ORM\Column(type="ulid", unique=true)
     * @ORM\GeneratedValue(strategy="CUSTOM")
     * @ORM\CustomIdGenerator(class=UlidGenerator::class)
     */
    private $id;

    // ...

    public function getId(): ?Ulid
    {
        return $this->id;
    }

    // ...

}

New in version 5.2: The ULID type and generator were introduced in Symfony 5.2.

When using built-in Doctrine repository methods (e.g. findOneBy()), Doctrine knows how to convert these ULID types to build the SQL query (e.g. ->findOneBy(['user' => $user->getUlid()])). However, when using DQL queries or building the query yourself, you’ll need to set ulid as the type of the ULID parameters:

// src/Repository/ProductRepository.php

// ...
class ProductRepository extends ServiceEntityRepository
{
    // ...

    public function findUserProducts(User $user): array
    {
        $qb = $this->createQueryBuilder('p')
            // ...
            // add 'ulid' as the third argument to tell Doctrine that this is an ULID
            ->setParameter('user', $user->getUlid(), 'ulid')

            // alternatively, you can convert it to a value compatible with
            // the type inferred by Doctrine
            ->setParameter('user', $user->getUlid()->toBinary())
        ;

        // ...
    }
}

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.