Laravel Interview Questions

Are you preparing yourself to take on your career as a Laravel Developer but worried about cracking the Laravel interviews successfully? Then you have come to the right place. We know what it takes to crack Laravel job interviews with success and that is why we have a team of experts and former interviewers who have formed a set of 15 Laravel interview questions and answers that will assist you cracking your next Laravel job interview with flying colours.

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Intermediate

Laravel is a new generation PHP web framework. It’s been developed by Taylor Otwell back in 2011 and intended for the development of web application. It follows the MVC model, that is a set of classes that do makes developers life easier. it’s been designed with focus to create an application which is simple, elegant and well structured. It’s a free, open-sourced framework with current stable release 5.7. With Laravel developer need to think less about setup, architecture, and dependencies of a project and go straight into the project.

Laravel has a framework called Lumen which is a micro-framework built on Laravel’s top components. It’s a perfect option for building a Laravel based microservice application.

Pros:

  1. Use of Composer: To manage project dependencies Laravel uses Composer. Which allows the developer to just mention the package name, version, and pre-built functionalities are ready to use into your project which makes it a prominent candidate for fast building application.
  1.  Blade template: Blade templating engine is easy to learn and use. It helps one when working with typical PHP/HTML languages. Laravel web development enables the composer of the plain codes PHP in a layout shape hence improving the execution of usage difficulties.
  1. Great community support and tutorial available: Key learning tool to learn Laravel is Laracast. It contains paid and free both videos.
  1. Eloquent ORM: Object Relational Mapper, in Laravel Eloquent is used for the same, which implements the active record pattern and is used to interact with the relational database. It comes as a package.
  1. Artisan support: It’s a built-in command line tool provided by laravel. One can perform majorly repetitive and tiresome programming task with the help of artisan. Laravel provides some in-built commands with the functionality to create custom commands.
  1. Migration System database: Laravel schema allows developers to build database tables, add columns along with indices via just writing a simple migration script.
  1. Reverse Routing: In Laravel reverse routing is generating URL’s based on route declarations. Reverse routing makes your application so much more flexible.
  2. Along with it, Laravel has many great features like Routing, Inbuilt caching support, Queue support, dependency injection, multiple file system support, integration with mail service, etc.

Cons:

  1. Legacy system migration to Laravel is not an easy task.
  2. Laravel documentation is heavy.
  3. Sometimes upgrades are not so smooth.
  4. It often lacks in providing the mobile app richness and because of that most developers use the framework as backend JSON API only.

Event is an action that’s been recognised by the program and can be handled by the program itself. Laravel events work on Observer- subscriber pattern. Laravel event classes are stored in app/Events directory whereas listeners are stored in app/listeners directory. Events decouple various aspect of application since a single event can handle multiple listeners that are independent.

Let’s understand with an example: When a system receives payment of an order you would like to trigger a notification. With the introduction of the event here, you need not to couple payment processing code rather just need to raise an event PaymentReceived and listener can receive and generate a notification.

Event can be generated via Artisan command.

php artisan event generate.

Validation in programming is necessary to make sure the system is receiving the expected data. Like other frameworks, Laravel also have validations.

ValidatesRequests is the trait which is been used by Laravel classes for validating input data. For storing data we generally use create or store methods that we can define at Laravel routes along with a get method.

Laravel Validate method is available in Illuminate\Http\Request object. If validation rule passes, your code will execute properly. If it fails then an exception will be thrown and the user will get a proper error response for HTTP requests whereas JSON response will be generated if the request was an AJAX request.  

Basic example of how validation rules are defined will be like :

/**
* Store a post.
*
* @param  Request $request
* @return Response
*/
public function store(Request $request)
{
   $validatedData = $request->validate([
       'title' => 'required|unique:posts|max:255',
       'body' => 'required',
   ]);
}

Title and body will be a required field. Validation rule execution will be sequential so if unique fails then 255 characters validation will not be executed.

Composer is a dependency manager. If it's not installed on your system, 

  1. can be installed via following steps mentioned https://getcomposer.org/download/.
  2. Once Composer is installed on your system create a project directory for Laravel project.
  3. Now move to the path where Laravel directory is created and execute the following command.

composer create-project laravel/laravel –-prefer-dist

This command will be installing Laravel in the current directory

  1. To start Laravel, execute the following command

php artisan serve 

It will start the Laravel development server.

  1. At browser now run http://localhost:8000/

Server Requirement to install Laravel 5.6

  • PHP >= 7.1.3
  • OpenSSL PHP Extension
  • PDO PHP Extension
  • Mbstring PHP Extension
  • Tokenizer PHP Extension
  • XML PHP Extension
  • Ctype PHP Extension
  • JSON PHP Extension

PHP artisan is a command based (CLI) tool in laravel, It provides a good number of commands that can help us to build an application faster. Artisan commands are available by default for all important operation like database seeding, migration, cache configuration to clearing cache, setting application namespace, event and key generation, queueing, running scheduled tasks, etc.

To check available artisan command list, we can use the command :

php artisan list

Some important Laravel artisan commands are:

  • Php artisan help
  • php artisan tinker
  • php artisan make
  • php artisan –versian
  • php artisan migrate
  • php artisan make:model model_name
  • php artisan make:controller controller_name
  • php artisan make:auth
  • php artisan cache:clear
  • php artisan db:seed
  • php artisan app:name
  • php artisan event:generate

To create a new (custom) php artisan command:

php artisan make:command

Middleware provides a mechanism to filter HTTP request, entering your application. Basic middleware can be explained with authentication. Laravel includes middleware for authentication.  if a user is unauthenticated then we want to redirect to the login page and if it’s authenticated then we will allow proceeding further action. This can be easily done with middleware.

php artisan make:middleware middleware_name  is the artisan command to define a new middleware in your application. By default, all middleware will be stored in app/Http/Middleware directory.  To run middleware during every HTTP request to your application, you can list the middleware class in the $middleware property of your app/Http/Kernel.php class. To assign middleware to specific routes assign it in key-value pair at app/Http/Kernel.php class $routeMiddleware property.

Laravel route helps to build SEO friendly request URL. Most basic Laravel route accepts 2 parameters i.e. URI and closure.

Route::get('hello', function () {
   return 'Hello World';
});

All Laravel routes are defined in route file in routes directory. For web interface routes will be defined in routes/web.php whereas the routes in routes/api.php are stateless and are assigned the api middleware group.  

Available Route Methods

Route::get($uri, $callback);

Route::post($uri, $callback);

Route::put($uri, $callback);

Route::patch($uri, $callback);

Route::delete($uri, $callback);

Route::options($uri, $callback);

Event is an occurrence that is to be handled by the program itself. Laravel events provide observer implementation in the application, that allows us to subscribe and listen to various events occurring in the application. Event classes are stored in app/Events directory whereas listeners classes will be stored in app/Listeners.

You can generate events manually as well as with artisan command. Artisan command to generate event is php artisan event:generateEvents and listeners should be listed in EventServiceProvider class. With artisan command, new event and listeners will be created whereas older one will be left untouched.

Laravel uses Blade templating engine. Blade is a powerful but simple templating engine of Laravel. Blade allows you to use plain php code into view and it compiles and cached view until it’s modified. Blade view files are stored in resources/views directory with extension .blade.php.

An example of blade file is :

<!-- /resources/views/alert.blade.php -->
<div class="alert alert-danger">
   {{ $slot }}
</div>

In the variable $slot we can assign any value which we want to inject to component. Component looks like:

@component('alert')
   <strong>Whoops!</strong> Something went wrong!
@endcomponent
@component is the blade directive here.

First let's understand CSRF - It's cross-site request forgery attack. Cross-site forgeries are a type of malicious exploit where unauthorized commands can be executed on behalf of the authenticated user. Laravel generates a CSRF "token" automatically for each active user session. This token is used to verify that the authenticated user is the one actually making the requests to the application.

<form method="POST" action="/profile">
   @csrf
   ...
</form>

If you're defining an HTML form in your application you should include a hidden CSRF token field in the form so that middleware (CSRF Protection middleware) can validate the request. VerifyCsrfToken middleware is included in web middleware group. @csrf blade directive can be used to generate the token field.

If using JS driven application then you can attach your js HTTP library automatically attach the CSRF token with every HTTP request. resources/js/bootstrap.js is the default file which registers value of csrf-token meta tag with HTTP library.

To remove URIs from CSRF in verifyCsrfToken we can use $except property where can provide URLs which we want to exclude.

Migrations are like version control for the database. With migration team can easily modify the database schema, migrations are paired with Laravel’s schema builder to easily build application’s db schema. With Laravel Schema facade creating and manipulating tables across the application is very easy. Artisan command to create migration schema is php artisan make:migration create_employeess_table. New migrations will be stored in database/migrations directory. Each migration will along with migration name contains the timestamp of the creation of file which helps Laravel to order migrations.

The --table and --create options may be used to indicate the name of the table and whether the migration will be creating a new table. These options pre-fill the generated migration stub file with the specified table:

php artisan make:migration create_employees_table --create=employees

php artisan make:migration add_departments_to_employee_table --table=employees

Laravel facades provide a "static" interface to classes that are available in the application's service container. All of Laravel's facades are defined in Illuminate\Support\Facades namespace. Facades are easy to use and don’t require injection so we can use many facades in one class. The benefit of using facade class is its expressive syntax, maintaining more testability and flexibility than traditional static methods of classes.

Access facade like:

use Illuminate\Support\Facades\Cache;
Route::get('/cache', function () {
   return Cache::get('key');
});

Laravel service container is a great and powerful tool to manage dependencies and to perform dependency injection. So now the question comes what is dependency injection - In classes dependencies will be injected through either constructor or setter method.

<?php
namespace App\Http\Controllers;
use App\Employee;
use App\Repositories\EmployeeRepository;
use App\Http\Controllers\Controller;
class EmployeeController extends Controller
{
   /**
    * The employee repository implementation.
    *
    * @var EmployeeRepository
    */
   protected $employees;
   /**
    * Create a new controller instance.
    *
    * @param  EmployeeRepository  $employees
    * @return void
    */
   public function __construct(EmployeeRepository $employees)
   {
       $this->employees = $employees;
   }
   /**
    * Show the profile for the given employee.
    *
    * @param  int $id
    * @return Response
    */
   public function show($id)
   {
       $employee = $this->employees->find($id);
       return view('employee.profile', ['employee' => $employee]);
   }
}

Here EmployeeController needs to retrieve information of employee from a data source so we have injected a service that will provide information of the employee.

Before understanding eloquent let’s first understand ORM - Object Relational Mapping, it’s a programming technique for converting data between a relational database and object-oriented programming, we can say it an object-relational mapper as well.

Eloquent is an ORM used in Laravel. It provides simple Active record implementation working with the database. Each database table has their Model which used to interact with the table.  Eloquent provides many types of relationships:

  • One to One
  • Many to one
  • One to Many
  • Many to Many
  • Has one through
  • Has many through

Description

Are you preparing yourself to take on your career as a Laravel Developer but worried about cracking the Laravel interviews successfully? Then you have come to the right place. We know what it takes to crack Laravel job interviews with success and that is why we have a team of experts and former interviewers who have formed a set of 15 Laravel interview questions and answers that will assist you cracking your next Laravel job interview with flying colours.
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