Awesome Laravel Interview questions

Get well-prepared for your next Laravel career and push your Laravel knowledge to a new level, super advanced!

This will focus on 100% backend questions based on Laravel framework.

Languages

• English (this)
• Vietnamese (coming soon)
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Other Recommendations

• PHP interview questions
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  • Main focus: MySQL/MariaDB or PostgreSQL
• System Designs

Table of Contents

Basic

1. Migrations & Seeders
2. Routing
3. Middlewares
4. Requests
5. Controllers
6. Models / Eloquents / Query Builders

Deep-dive

1. Service Provider
2. Service Container
3. Facade
4. Artisan Commands
5. Queue
6. Events / Listeners
7. Task Scheduling - Cron Job
8. Test
   1. Unit tests
   2. Feature tests

Basic Questions

1/ Migrations & Seeders

1. Use cases of Migrations & Seeders?
   • Use Migrations for actions that affecting table's structure (CREATE, ALTER, DROP)
   • Use Seeders for actions that affecting table's data (INSERT, UPDATE, DELETE)
2. When creating a Migration to create a table, what are the recommendations for the new table?
   • Use the default timestamps() method to create created_at and updated_at which built-in in Eloquent, helps to track
   • Use the softDeletes(), avoid hard-delete on the Production - data is king.
3. Can I put multiple statements in a same Migration?
   • No, avoid to do so. We never know if a Migration went wrong, once it goes wrong, we can't hit the migrate command again because there would be some statement that already ran in the previous migration.
   • Keep the Migration as small as possible.
4. Which helpers that I can use for Seeders?
   • Faker
   • Factory

2/ Routing

1. Best practices of Laravel's Routes?
   • Using kebab-case for the route (eg: my-details, user-details/profile,...)
   • Follow this register Route::get('my-details', [MyDetailsController::class, 'index']);
   • Group the same prefix routes
2. What is the main benefit of the Route::resource(..)?
   • To register CRUD routes in 1 line only
3. How to optimize the routes computing times?
   • By caching it, using php artisan route:cache

3/ Middlewares

1. Pros and Cons of registering your custom middleware in protected $middleware?
   • Pros: my middleware will be triggered for every requests
   • Cons: I can't access to sessions or cookies because it will be computed in a later Middlewares (web group)
2. Usage of throttle?
   • throttle:300,1 means we only allow 300 requests in 1 minute
   • Use it to avoid spaming/hijacking requests
3. We can handle things before the request is going to Controller, but can we handle something after the process of Controller finished?
   • Yes, basically we can invoke $next($request) and the line below, we can add our custom actions

   // Sample Code
   public function handle(Request $request, Closure $next) {
       $result = $next($request);
       // do your own logic here
       Log::info('Request log:' . json_encode($result));
       
       return $result;
   }

4/ Requests

1. Do you use custom FormRequest? What are the benefis of using FormRequest.
   • A single place to validate the request: authorization & data validation before going to Controller.
   • Request can only reach to the Controller once everything is validated (GOOD)
2. How can I perform some actions after the authorization check or validation check?
   • Use passedAuthorization() and passedValidation() hooks to achieve that.
3. What can I do more for my custom FormRequest class?
   • You can implement getter methods eg getAccount(), getTopic() and make them return the exact type, so from your Controller to can retrieve the needful typed instances. A great help for IDE as well.

5/ Controllers

1. Best practices of Controller?
   • Use FormRequest to validate all of the data, then from Controller, we can start the processing without any checking.
   • Prefer Dependency Injection (ideally in the method's parameters)
   • If there are too much things to handle, create multiple services to handle instead of putting all logic in 1 place
   • Always prepare the return type of Controller's methods (JsonResponse, ViewResponse,...)
   • Follows Laravel's Resource structure (index, show, create, update,...)
2. How I can invoke another Controller's method?
   • You don't, and it is super bad practice. You need to extract the login into a Service, then inject the Service where you want to use.
   • Following DRY - Don't repeat yourself
3. Can I register my Controller without any methods in the routes file?
   • You can, then you need to implement the __invoke() method in order to make it work.

6. Models / Eloquents / Query Builders

1. How to avoid N+1 problems?
   • By using eager-loading.
2. How to trace queries of Eloquents / Query Builders?
   • You can use Laravel Debugbar, Ray, Telescope,...
   • For PROD applications, you can use DataDog, BlackFire,...
3. How to know which fields/columns that a single Eloquent Model has?
   • We need to manually add the phpDoc and maintain the @property there. And it is IDE-friendly.

Continue....

Deep-dive Questions

Coming soon...

Contributions

• Seth Phat
• ...