GUID

GUID (Globally Unique Identifier) is Microsoft’s implementation of UUID, formatted in uppercase for compatibility with Windows and .NET ecosystems.

What is GUID?

GUID is functionally identical to UUID version 4 but follows Microsoft’s naming and formatting conventions:

• Uppercase formatting: Uses uppercase hexadecimal characters (A-F, 0-9)
• Same structure as UUID: 128-bit identifier with standard format
• Microsoft compatibility: Matches .NET’s System.Guid output
• RFC 4122 compliant: Follows UUID v4 specification

Example GUID: 550E8400-E29B-41D4-A716-446655440000

GUID vs UUID

The only difference is formatting:

Aspect	GUID	UUID
Format	550E8400-E29B-...	550e8400-e29b-...
Case	Uppercase	Lowercase
Ecosystem	Microsoft/.NET/Windows	Unix/Web/General

Configuring GUID Generator

Enable GUID generation in your application:

use Cline\StronglyTypedId\Enums\GeneratorType;
use Cline\StronglyTypedId\Facades\IdGenerator;

IdGenerator::setGenerator(GeneratorType::Guid);

Now all ID generation will use GUIDs:

$userId = UserId::generate();
// e.g., "550E8400-E29B-41D4-A716-446655440000"

Interoperability with Microsoft Systems

.NET Integration

GUIDs are compatible with .NET’s System.Guid:

// C# code
var guid = Guid.Parse("550E8400-E29B-41D4-A716-446655440000");
var newGuid = Guid.NewGuid();

SQL Server

Store GUIDs in SQL Server’s native uniqueidentifier type:

CREATE TABLE users (
    id UNIQUEIDENTIFIER PRIMARY KEY DEFAULT NEWID(),
    name NVARCHAR(255)
);

Web Services

When interfacing with Microsoft web services:

$response = Http::post('https://api.microsoft.com/endpoint', [
    'userId' => $userId->toString(), // Uppercase GUID
]);

Case Sensitivity Considerations

PHP strings are case-sensitive by default:

$guid1 = UserId::fromString('550E8400-E29B-41D4-A716-446655440000');
$guid2 = UserId::fromString('550e8400-e29b-41d4-a716-446655440000');

// Different string values
$guid1->toString() === $guid2->toString(); // false

// Normalize for comparison
mb_strtoupper($guid1->toString()) === mb_strtoupper($guid2->toString()); // true

Database Storage

Store GUIDs as CHAR(36) or use Laravel’s uuid() method:

Schema::create('users', function (Blueprint $table) {
    $table->uuid('id')->primary();
});

For case-insensitive comparison:

Schema::create('users', function (Blueprint $table) {
    $table->char('id', 36)
        ->collation('utf8mb4_unicode_ci')
        ->primary();
});

Braces Notation

Microsoft tools sometimes use GUIDs with braces:

$userId = UserId::generate();
$guidWithBraces = '{' . $userId->toString() . '}';
// Result: "{550E8400-E29B-41D4-A716-446655440000}"

Use Cases

Choose GUID when:

• Interfacing with .NET applications
• SQL Server databases
• Azure services
• Windows-based systems
• APIs requiring uppercase UUID format

Choose UUID when:

• Web standards compliance
• Unix/Linux environments
• Existing lowercase systems
• Non-Microsoft tech stacks