Constructor Injection in Laravel: A Clean Way to Inject Dependencies

If you're working with services or repositories in your Laravel app (especially with Livewire or Inertia components), you'll likely want to use constructor injection.

Constructor injection is a way to pass dependencies into a class through its constructor, keeping your code clean, testable, and easy to manage.

A Basic Example

use App\Services\WeatherService;

class WeatherController extends Controller
{
    protected WeatherService $weather;

    public function __construct(WeatherService $weather)
    {
        $this->weather = $weather;
    }

    public function show()
    {
        return $this->weather->getForecast();
    }
}

Laravel’s service container automatically resolves the dependency for you—no need to manually instantiate anything.

Why Use Constructor Injection?

• Cleaner code: Keeps business logic out of constructors.
• Easier testing: You can easily mock dependencies in tests.
• Better readability: It’s clear what dependencies a class needs.
• Great with single-responsibility services: Especially common when using the TALL stack to keep Livewire components slim.

Tip for Livewire

When using Livewire, you can’t inject services via the constructor because Livewire serializes components. Instead:

Use the mount() method

Or grab the service using the container: app(MyService::class)

But in controllers, jobs, listeners, and service classes—constructor injection is gold.