Laravel backend development interview questions with answers
Intermediate & Advanced Level backend development interview Questions with Answers
1. What is the purpose of service providers in Laravel?
To create a service provider:
php artisan make:provider MyServiceProvider
Then, register it in config/app.php:
'providers' => [
App\Providers\MyServiceProvider::class,
];
Inside MyServiceProvider.php:
public function register()
{
$this->app->bind('MyService', function () {
return new \App\Services\MyService();
});
}
2. How does Laravel handle dependency injection?
Answer: Laravel resolves dependencies automatically via the Service Container.
Example:
class UserController extends Controller
{
protected $userService;
public function __construct(UserService $userService)
{
$this->userService = $userService;
}
public function index()
{
return $this->userService->getAllUsers();
}
}
Laravel automatically resolves UserService from the service container.
3. What are Laravel facades, and how do they work?
Answer: Facades provide a static-like interface to classes in the service container.
Example: Creating a custom facade:
namespace App\Facades;
use Illuminate\Support\Facades\Facade;
class MyServiceFacade extends Facade
{
protected static function getFacadeAccessor()
{
return 'MyService';
}
}
Register in config/app.php:
'aliases' => [
'MyService' => App\Facades\MyServiceFacade::class,
];
Usage:
MyService::doSomething();
4. Explain the difference between hasManyThrough and hasOneThrough relationships in Eloquent.
Answer:
hasManyThrough: A one-to-many relationship through an intermediary table.
hasOneThrough: A one-to-one relationship through an intermediary table.
Example:
class Country extends Model
{
public function posts()
{
return $this->hasManyThrough(Post::class, User::class);
}
}
Here, Country has many Posts through User.
5. What is a Laravel Observer, and when should you use it?
Create an observer:
php artisan make:observer UserObserver --model=User
Inside UserObserver.php:
public function creating(User $user)
{
$user->uuid = Str::uuid();
}
Register in EventServiceProvider.php:
protected $observers = [
User::class => UserObserver::class,
];
6. How can you prevent mass assignment vulnerabilities in Laravel?
Answer: Define $fillable or $guarded in models.
protected $fillable = ['name', 'email', 'password'];
Or use $guarded to block specific fields:
protected $guarded = ['admin'];
7. What is the difference between policies and gates in Laravel authorization?
Answer:
Gates: Simple authorization logic using closures.
Gate example:
Gate::define('edit-post', function ($user, $post) {
return $user->id === $post->user_id;
});
Usage:
if (Gate::allows('edit-post', $post)) { /* ... */ }
Answer: Batching allows grouping jobs and handling them as a batch.
use Illuminate\Bus\Batch;
use Illuminate\Support\Facades\Bus;
$batch = Bus::batch([
new ProcessOrderJob(1),
new ProcessOrderJob(2)
])->dispatch();
09. What is event broadcasting in Laravel, and how do you implement it using WebSockets?
Answer: Event broadcasting allows real-time updates via WebSockets.
Install Pusher: composer require pusher/
pusher-php-server
1. Configure .env:
BROADCAST_DRIVER=pusher
2. Create an event:
php artisan make:event MessageSent
3. Dispatch the event:
broadcast(new MessageSent($message));
10. What is the purpose of Lazy Loading vs. Eager Loading in Eloquent ORM?
Answer:
Lazy Loading: Loads related data when accessed.
Eager Loading: Loads related data upfront.
Example:
// Lazy Loading
$user = User::find(1);
$posts = $user->posts; // Runs extra query
// Eager Loading
$user = User::with('posts')->find(1); // Single query
11. How does Laravel handle API rate limiting?
Answer:
Using throttle middleware:
Route::middleware('throttle:60,1')->get('/api/data', function () {
return response()->json(['message' => 'Success']);
});
12. Explain the concept of Headless Laravel and its benefits.
Answer:
Headless Laravel is used as a backend API without a frontend.
Benefits:
Better API performance.
Can be used with frontend frameworks like React, Vue, etc.
13. What is the difference between singleton, scoped, and transient bindings in the Laravel service container?
Answer:
$this->app->singleton(Service::class, function () {
return new Service();
}); // Single instance
$this->app->scoped(Service::class, function () {
return new Service();
}); // Per request
$this->app->bind(Service::class, function () {
return new Service();
}); // New instance every time
14. How do you secure an API in Laravel using Laravel Passport or Sanctum?
Answer: Install and configure Laravel Sanctum:
composer require laravel/sanctum
php artisan vendor:publish --provider="Laravel\Sanctum\
SanctumServiceProvider"
php artisan migrate
Protect routes:
Route::middleware('auth:sanctum')->get('/user', function (Request $request) {
return $request->user();
});
15. How do you implement repository patterns in Laravel?
Answer:
Create an interface:
interface UserRepositoryInterface {
public function all();
}
Implement the interface:
class UserRepository implements UserRepositoryInterface {
public function all() {
return User::all();
}
}
Bind in AppServiceProvider.php:
$this->app->bind(UserRepositoryInterface::class, UserRepository::class);
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