Working with PHP Attributes: Modern Metadata

Introduced in PHP 8.0, attributes provide a structured way to add metadata to your code declarations. They replace the docblock comments traditionally used for this purpose.

Basic Attribute Syntax

#[Attribute]
class Route {
    public function __construct(
        public string $path,
        public string $method = 'GET'
    ) {}
}

#[Route('/products', 'GET')]
class ProductController {
    #[Route('/{id}', 'GET')]
    public function show(int $id) {}
}

Reading Attributes with Reflection

$reflectionClass = new ReflectionClass(ProductController::class);
$attributes = $reflectionClass->getAttributes();

foreach ($attributes as $attribute) {
    $route = $attribute->newInstance();
    echo "Path: " . $route->path . "\n";
    echo "Method: " . $route->method . "\n";
}

Common Use Cases

• Routing: Define API endpoints
• Validation: Add validation rules to properties
• ORM mapping: Map classes to database tables
• Serialization: Control how objects are serialized
• Dependency Injection: Mark injectable services

Attribute Targets

You can restrict where attributes can be used:

#[Attribute(Attribute::TARGET_CLASS | Attribute::TARGET_METHOD)]
class MyAttribute {}

Built-in PHP Attributes

PHP includes several useful attributes:

#[Deprecated("Use newMethod() instead")]
#[AllowDynamicProperties]
#[ReturnTypeWillChange]

Attributes provide a cleaner, more maintainable approach to metadata than docblock comments, with proper syntax validation and IDE support.