Technical Job Interview questions 2022

Interview Questions I remembered #

The kind of questions I want to write about are not the “describe yourself in a three minutes” or “explain your experience” questions. I want to rethink some technical interview questions I was asked and could or could not answer at that point in time.

Laravel Questions #

What Laravel Feature do you love about Laravel 9? #

That question should have been easy. One of the big features are the new accessors and mutators ¹. I kinda dislike getters and setters anyway, so I don’t use them. The next big feature is the usage of Enums ², which I don’t use in practice because I can’t use them as array keys, which might change in the future, but until that is fixed I get quite frustrated about this little drawback to honestly state it in an interview ³. Every other new feature I found very small, and the only one I am looking forward to using is the str() helper function which replaces the Str::of().

What Feature do you miss about Laravel? #

I think Laravel uses too many provider / list files that are not easier or less magic than other implementations. The auto-discovery of event listener ⁴ is one way to replace one provider with something easier; another feature that would get rid of the route file would the Spring (Kotlin Framework) inspired Route binding using Annotations / Attributes ⁵.

In PHP Annotations are often used (at least by me) to type-hint methods and properties. For example, if I define a relation in Laravel I type-hint the corresponding relation attribute call, now I have typed $game->rounds() which returns a query builder, and $game->rounds which returns the collection ($game->rounds()->get()).

/**
 * @property \Illuminate\Support\Collection rounds
 * @see \App\Models\Game::rounds()
 */
class Game extends Model
{  
    public function rounds(): \Illuminate\Database\Eloquent\Relations\HasMany
    {
        return $this->hasMany(Round::class);
    }
...

But since PHP 8, Attributes are a new feature. And they are offering quite some opportunities ^{6 7}. Besides the inconvenient naming, I like the idea and can’t wait for Attributes to replace the route file ⁸. (For anyone who misses the route file for an overall overview has never seen a big route file and does not know the php artisan route:list command)

use Spatie\RouteAttributes\Attributes\Get;

class MyController
{
    #[Get('my-route')]
    public function myMethod()
    {
    }
}

What standard changes or libraries do you apply to every Laravel Project? #

Most times I join existing projects, and my private projects are most times to test something out and therefore focused on whatever I want to try out, and not follow my favorite Laravel styles. I will try to add something to this list, but if you have an answer to this question, I am curious to read it.

Clean up Laravel Sail and switch to Prostgres Not only because it saves some (for me usually not needed) Docker space, but because Prostgres is the better choice for a relational Database (Enums, Money Types, in-json search, (and the Docker Image works great for M1)).

Write a UUID Traid Because writing Str::uuid() on every model creation is annoying. I use uuids to obscure the id towards the client, but use the numeric id for relationships.

trait HasUuid
{
    // fill uuid column
    protected static function booted()
    {
        static::created(fn ($model) => $model->uuid = Str::uuid());
    }

    // set route key name
    public function getRouteKeyName()
    {
        return 'uuid';
    }
}

How does a request live through Laravel? #

One of my favorite questions - so I spend some time digging into the Laravel Code to find out.

Starting the Application public/index.php

Laravel said $kernel = $app->make(Kernel::class); and there was a Kernel. Out of the box, this is the app/Http/Kernel.php. In this step the Application (which holds path information, registers Providers…) ⁹ and Router (which is the class behind Route Facade) are instantiated.

Handling app/Http/Kernel.php The Kernel extends vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php, and the important method call is handle(). In the handle function the Kernel tries to send the Request through the Router, configure error handling, configure logging, and detect the application environment. After this, and before the call returns the response the RequestHandled Event is dispatched.

Pipelines app/Http/Kernel.php

The Pipeline Design Pattern is a software design pattern that provides ability to execute a sequence of operations where data flows through a sequence of tasks or stages. ¹⁰

Every Middleware in Laravel is a pipe the request is sent though and a small task is performed on the Request. In this step the HTTP Session, CSRF Token, Maintenance Prevention, and whatever Middleware you added in the Kernel.

Dispatch to Router vendor/laravel/framework/src/Illuminate/Routing/Router.php

The Router matches the Route from the Routes defined in the routes/* files (or other places if specified), dispatches a RouteMatched Event, and again uses a Pipeline to run through the Route specific Middlewares which might include Authentication or Authorisation.

Run route, run vendor/laravel/framework/src/Illuminate/Routing/ControllerDispatcher.php

The Route matches its Controller or Callback, whatever convention was followed. Then the Controller Dispatcher tries to satisfy the Method Dependencies ¹¹, e.g. if you injected a Repository or FormRequest. For every Parameter (besides the Model Bindings), a Reflection Class is created and after that an Instant of that class is made. Some magic later the FormRequestServiceProvider kicks in (what here happens is Container Magic. Laravel Container are something interesting, something that cause itchy bugs, and something I need to dedicate learning time to understand - so this is magic for me at the current point in time).

Validation vendor/laravel/framework/src/Illuminate/Foundation/Providers/FormRequestServiceProvider.php

The Validation is triggered in the vendor/laravel/framework/src/Illuminate/Validation/ValidatesWhenResolvedTrait.php first checking the Authorization, followed by the Validation. If either is not specified, a default is created.

Controller

After the Dependency Injection of everything the Controller needs, the business code is executed, the Controller returns e.g. a Resource.

Wrapping into a Response vendor/laravel/framework/src/Illuminate/Routing/Router.php

The Response is wrapped into a Response again in the Router - so from Code Perspective we are already on the way back. From that point on there is not much more to write, the Response bubbles up the way it came and is returned to the Kernel in which it is the (Symfony) Response to build Header and Body and send the information.

PHP Questions #

What PHP 8 Feature do you like the most? #

A lot! Using Laravel examples:

Constructor Properties, especially for Events: Method parameters can now include the declaration of public and private properties.

class PlayerJoined
{
    public function __construct(public Game $game, public Player $player)
    {
    }
}

Union Types are great for Events as well

class UpdatePlayerInformation
{
    public function handle(PlayerJoined|PlayerLeft $event): void
    {
    }
}

Nullsafe Operator is just neat. $player->user ? $player->user->name : null = $player?->user->name

Match Expression a bit better switch statement

 $score = match ($playerRole) {
    'WEREWOLF','MINION'  => $werewolfScore,
    'TANNER'             => $tannerScore,
    'WATCHER'            => 0,
    default              => $villagerScore,
};

// match(true) is the same half shady, half awesome solution as switch(true)
$score = match (true) {
    $diffFromTarget <= 5 => 10,
    $diffFromTarget <= 10 => 3,
    $diffFromTarget <= 20 => 1,
    default => 0,
};

Dev Tool Questions #

Your Query is slow, how to tackle the task to improve it? #

A basic, “do you know your tools?” question.

What can cause long client-side waiting time? Client Issues, long boot time on Laravel side, long Query time, third Party Api calls … The Flow Chart I would follow would like: Is it a Backend problem? Can I replicate the

How can I debug performance? Simulate on Dev Environment (Seeders, Feature Tests), Postman debugging, Laravel Debug bar ¹², Logging of benchmarks, Logging with third party analytics (e.g. Performance logging in Sentry)

Bonus hint if you don’t use the Debugbar: Illuminate fires an illuminate.query Event that you can listen for ( preferably in a Service Provider).

Event::listen('illuminate.query', fn($query) => var_dump($query));