คำถามสัมภาษณ์ PHP Laravel Developer 2026: คู่มือเตรียมตัวฉบับสมบูรณ์

// ปัญหา N+1: 1 query สำหรับ posts + N queries สำหรับ authors
$posts = Post::all();
foreach ($posts as $post) {
    echo $post->author->name; // ทริกเกอร์ query ต่อ post
}

// วิธีแก้: Eager load ด้วย with()
$posts = Post::with('author')->get(); // รวม 2 queries
foreach ($posts as $post) {
    echo $post->author->name; // ไม่มี query เพิ่มเติม
}

use Illuminate\Database\Eloquent\SoftDeletes;

class Post extends Model
{
    use SoftDeletes;
    
    // record ที่ถูก soft-delete จะถูกยกเว้นโดย default
    // เพื่อรวมมัน:
    // Post::withTrashed()->get();
    // เพื่อดึงเฉพาะที่ถูกลบ:
    // Post::onlyTrashed()->get();
}

public function register(): void
{
    // bind: Instance ใหม่ทุกครั้งที่ resolve
    $this->app->bind(PaymentService::class, function ($app) {
        return new PaymentService($app->make(StripeClient::class));
    });
    
    // singleton: Instance เดียวกันตลอด request
    $this->app->singleton(CartService::class, function ($app) {
        return new CartService();
    });
    
    // instance: Bind instance ที่มีอยู่แล้ว
    $analytics = new AnalyticsService('UA-xxxxx');
    $this->app->instance(AnalyticsService::class, $analytics);
}

public function register(): void
{
    $this->app->when(PhotoController::class)
        ->needs(Filesystem::class)
        ->give(function () {
            return Storage::disk('photos');
        });

    $this->app->when(VideoController::class)
        ->needs(Filesystem::class)
        ->give(function () {
            return Storage::disk('videos');
        });
}

use Illuminate\Support\Facades\Gate;

public function boot(): void
{
    // Gate: Closure ธรรมดา
    Gate::define('edit-settings', function (User $user) {
        return $user->isAdmin();
    });
}

// app/Policies/PostPolicy.php
class PostPolicy
{
    public function update(User $user, Post $post): bool
    {
        return $user->id === $post->user_id;
    }
    
    public function delete(User $user, Post $post): bool
    {
        return $user->id === $post->user_id || $user->isAdmin();
    }
}

// การใช้งานใน controller
public function update(Request $request, Post $post)
{
    $this->authorize('update', $post);
    // หรือ: Gate::authorize('edit-settings');
}

use Illuminate\Support\Facades\Route;

Route::middleware('web')->group(function () {
    Route::post('/passkey/register', [PasskeyController::class, 'store']);
    Route::post('/passkey/authenticate', [PasskeyController::class, 'authenticate']);
});

// app/Http/Controllers/PasskeyController.php
use Illuminate\Support\Facades\Auth;
use Laravel\Passkey\Passkey;

class PasskeyController extends Controller
{
    public function store(Request $request)
    {
        $passkey = Passkey::createFor($request->user());
        return response()->json(['passkey' => $passkey]);
    }
    
    public function authenticate(Request $request)
    {
        $user = Passkey::authenticate($request->credential);
        Auth::login($user);
        return redirect('/dashboard');
    }
}

class ProcessPodcast implements ShouldQueue
{
    use Queueable;
    
    public $tries = 3;
    public $backoff = [60, 300, 600]; // Exponential backoff
    public $timeout = 120;
    
    public function __construct(public Podcast $podcast) {}
    
    public function handle(AudioProcessor $processor): void
    {
        $processor->process($this->podcast->audio_path);
    }
    
    public function failed(\Throwable $exception): void
    {
        // ส่งการแจ้งเตือนไปยัง admin
        Notification::route('mail', 'admin@example.com')
            ->notify(new JobFailed($this->podcast, $exception));
    }
}

// Dispatch job
ProcessPodcast::dispatch($podcast)
    ->onQueue('podcasts')
    ->delay(now()->addMinutes(5));

use Illuminate\Bus\Batch;
use Illuminate\Support\Facades\Bus;

public function import(Request $request)
{
    $jobs = collect($request->users)->map(function ($userData) {
        return new ImportUser($userData);
    });
    
    $batch = Bus::batch($jobs)
        ->then(function (Batch $batch) {
            // Job ทั้งหมดเสร็จสมบูรณ์
            Notification::send($batch->createdBy, new ImportCompleted());
        })
        ->catch(function (Batch $batch, \Throwable $e) {
            // ตรวจพบ batch job แรกที่ล้มเหลว
            Log::error('Batch failed', ['batch_id' => $batch->id]);
        })
        ->finally(function (Batch $batch) {
            // Batch รันเสร็จสิ้น
        })
        ->allowFailures()
        ->dispatch();
    
    return response()->json(['batch_id' => $batch->id]);
}

use App\Services\DiscountService;

test('calculates percentage discount correctly', function () {
    $service = new DiscountService();
    $result = $service->calculate(100, 'SAVE20');
    
    expect($result)->toBe(80.0);
});

// tests/Feature/Api/ProductTest.php
use App\Models\Product;
use App\Models\User;

test('authenticated users can create products', function () {
    $user = User::factory()->create();
    
    $response = $this->actingAs($user)
        ->postJson('/api/products', [
            'name' => 'Laravel Course',
            'price' => 99.99,
        ]);
    
    $response->assertStatus(201)
        ->assertJsonPath('data.name', 'Laravel Course');
    
    $this->assertDatabaseHas('products', [
        'name' => 'Laravel Course',
        'user_id' => $user->id,
    ]);
});

use App\Services\PaymentGateway;
use Mockery;

test('processes payment successfully', function () {
    $mock = Mockery::mock(PaymentGateway::class);
    $mock->shouldReceive('charge')
        ->once()
        ->with(100, 'tok_visa')
        ->andReturn(['status' => 'success', 'id' => 'ch_123']);
    
    $this->app->instance(PaymentGateway::class, $mock);
    
    $response = $this->postJson('/api/payments', [
        'amount' => 100,
        'token' => 'tok_visa',
    ]);
    
    $response->assertStatus(200)
        ->assertJsonPath('payment_id', 'ch_123');
});

// app/Services/ContentService.php
use Illuminate\Support\Facades\AI;

class ContentService
{
    public function generateSummary(string $content): string
    {
        $response = AI::chat()
            ->system('You are a helpful assistant that summarizes content.')
            ->user("Summarize this: {$content}")
            ->generate();
        
        return $response->text;
    }
    
    public function streamResponse(string $prompt)
    {
        return AI::chat()
            ->user($prompt)
            ->stream();
    }
}

use Illuminate\Routing\Attributes\Get;
use Illuminate\Routing\Attributes\Middleware;

#[Middleware('auth')]
class UserController extends Controller
{
    #[Get('/users/{user}')]
    public function show(User $user)
    {
        return view('users.show', compact('user'));
    }
    
    #[Get('/users/{user}/edit')]
    #[Middleware('can:edit,user')]
    public function edit(User $user)
    {
        return view('users.edit', compact('user'));
    }
}

app/
├── Domain/
│   ├── Orders/
│   │   ├── Actions/
│   │   │   └── CreateOrderAction.php
│   │   ├── Models/
│   │   │   └── Order.php
│   │   ├── Events/
│   │   │   └── OrderCreated.php
│   │   └── Services/
│   │       └── OrderService.php
│   └── Users/
│       ├── Actions/
│       ├── Models/
│       └── Services/
├── Http/
│   └── Controllers/
└── Providers/

interface UserRepositoryInterface
{
    public function find(int $id): ?User;
    public function findByEmail(string $email): ?User;
    public function create(array $data): User;
    public function paginate(int $perPage = 15): LengthAwarePaginator;
}

// app/Repositories/EloquentUserRepository.php
class EloquentUserRepository implements UserRepositoryInterface
{
    public function __construct(private User $model) {}
    
    public function find(int $id): ?User
    {
        return $this->model->find($id);
    }
    
    public function findByEmail(string $email): ?User
    {
        return $this->model->where('email', $email)->first();
    }
    
    public function create(array $data): User
    {
        return $this->model->create($data);
    }
    
    public function paginate(int $perPage = 15): LengthAwarePaginator
    {
        return $this->model->paginate($perPage);
    }
}

// app/Providers/RepositoryServiceProvider.php
public function register(): void
{
    $this->app->bind(
        UserRepositoryInterface::class,
        EloquentUserRepository::class
    );
}