PHP Attributes: Modern Metadata in Your Code

Since PHP 8, we’ve had attributes — a modern way to add metadata directly to classes, methods, or properties. Think of them like annotations in Java or decorators in Python.

What are Attributes?

Attributes let you “tag” parts of your code with extra information. Frameworks or libraries can then read these tags at runtime and act on them.

Example:

#[Route('/home', methods: ['GET'])]
class HomeController {
    // ...
}

Here, the Route attribute describes how this controller should be exposed.

How Do You Define an Attribute?

Attributes are just classes marked with #[Attribute].

use Attribute;

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

How to Read Attributes with Reflection

You can fetch and use attributes at runtime via the Reflection API:

$reflection = new ReflectionClass(HomeController::class);

// Get all attributes on the class
foreach ($reflection->getAttributes(Route::class) as $attr) {
    // Turn attribute into a real object
    $route = $attr->newInstance();

    echo $route->path;     // "/home"
    echo implode(',', $route->methods); // "GET"
}

This is how frameworks like Symfony or Doctrine process metadata and apply logic automatically.

Why Use Attributes?

• Cleaner than PHPDoc comments
• More flexible than marker interfaces
• Supported natively by PHP, no hacks needed

Where Are They Used?

• Symfony → #[Route] for controllers
• Doctrine ORM → #[Entity], #[Column] for database mapping
• Custom apps → logging, caching, validation rules

In short: Attributes bring structured, modern metadata to PHP. They’re concise, powerful, and built right into the language — and with reflection, they let your code adapt based on annotations.