// 18 Essential Laravel Interview Questions

Laravel's middleware serves as a conduit between the request and the response. It offers a method of looking into HTTP requests made to your application. For instance, Laravel's middleware ensures that your application's user is authenticated. The user will be redirected to the application's main login page if it is determined that they have not been authenticated.

For our needs, we can always develop new middleware. For example, the following artisan command can be used to create one:

php artisan make:middleware CheckFileIsNotTooLarge

The command will create a new middleware file in the app/Http/Middleware folder.

1. delete()
The delete function is used when we want to delete a record from the database table in Laravel.

Example:

$delete = Post::where('id', '=', 1)->delete();

2. softDeletes()

Deleting records permanently is not advisable. That's why Laravel uses a feature called SoftDelete. SoftDelete does not remove the records from the table; it only updates the delele_at value with the current date and time.

To use softDeletes, firstly, we have to add a given code to our required model file.

use SoftDeletes;
protected $dates = ['deleted_at'];

After this, we can use both cases.

$softDelete = Post::where('id', '=', 1)->delete();

OR

$softDelete = Post::where('id', '=', 1)->softDeletes();

Cross-Site Request Forgery security is also known as CSRF security. CSRF detects unauthorized system users making unauthorized attacks on web applications. For it to be able to verify all the operations and requests sent by an active authenticated user, the built-in CSRF plug-in is used to generate CSRF tokens.

The CSRF protection for a particular route can be disabled using the code above. We can do this by including that specific URL or Route in the $except variable found in the app\Http\Middleware\VerifyCsrfToken.php file.

Note: Commonly asked Laravel interview question.

PHP traits are a collection of methods that other classes can utilize. Like an abstract class, a trait cannot be instantiated by itself. In PHP, traits are created to overcome the restrictions of single inheritance. It enables developers to freely repurpose sets of methods across numerous independent classes with varying class hierarchies.

Once a trait has been defined, such as in the code above, it can be used by other classes such as:

class Post {  
use Sharable;  
}  
class Comment {  
use Sharable;  
}  

Moreover, if we wanted to create new objects from these classes, we would find a share() method available in both classes:

$post = new Post;  
echo $post->share(''); // 'share this item'   
$comment = new Comment;  
echo $comment->share(''); // 'share this item'  

Rate-limiting requests from a specific IP address is a process called throttling. This can also be used to thwart DDOS attacks. Laravel offers a middleware for throttling that can be added to routes and the global middleware's list to execute that middleware for each request.

For example, you can add it to a particular route:

Route::middleware('auth:api', 'throttle:60,1')->group(function () {
    Route::get('/user', function () {
        //
    });
});

Static-like interface classes are provided by Laravel Facades and are accessible from the application's service container. Laravel self-ships with various accessible facades and provides access to almost all of its features. However, facades make accessing a service directly from a container easier. It is described in the namespace Illuminate\Support\Facades. It is therefore simple to use.

After performing some operations on the fields retrieved from the database, accessors are a way to retrieve data from Eloquent. The first and last names of users, for instance, must be combined whenever data is fetched from eloquent queries, even though there are two fields for these names in the database.

We can accomplish that by developing an accessor similar to the one below:

public function getFullNameAttribute()          
{          
    return $this->first_name . " " . $this->last_name;          
}

If, for example, we need the combined name, we can call it $user->full_name because the code above adds another attribute (full name) to the model's collection. Before a field is saved to the database, it is possible to perform some operations on it using mutators.

For instance, we could write something like the following before saving it to the database:

public function setFirstNameAttribute($value)
{
    $this->attributes['first_name'] = strtoupper($value);
}

So, whenever we are setting this field to be of any value:

$user->first_name = Input::get('first_name');
$user->save();

It will capitalize the first_name and then save it to the database.

Note: Commonly asked Laravel interview question.

Some official packages provided by Laravel are given below:

Cashier
Laravel Cashier implements an expressive, fluid interface to Stripe and Braintree's subscription billing service. It controls almost all of the boilerplate subscription billing codes. The cashier can also manage coupons, subscription quantities, subscription swapping, grace periods for cancellation, and even create PDF invoices.

Envoy
The clean, simple syntax for defining frequent tasks that we execute on our remote servers is provided by Laravel Envoy. Moreover, users can quickly arrange tasks for deployment, Artisan commands, and more using syntax in the Blade style. Unfortunately, envoy only supports Mac and Linux operating systems.

Passport
With the aid of Laravel passport, API authentication was made simple. Additionally, it offers an instant Oauth2 server implementation for Laravel applications. Typically, Passport is built on top of the Alex Bilbie-maintained League OAuth2 server.

Scout
Laravel Eloquent models can now include full-text search thanks to Scout's straightforward, driver-based approach. Also, scout automatically maintains search indexes in sync with eloquent records using model observers.

Socialite
An expressive and fluid interface for OAuth authentication with Facebook, Twitter, Google, LinkedIn, and other services is provided by Socialite. It controls almost all of the boilerplate social authentication codes.

Note: Commonly asked Laravel interview question.

Database migration is similar to database version control, which enables the team to edit and share the application's database schema. The Laravel schema builder, which is used to create the application's database schema, is paired with database migrations.

It is a form of database version control. It makes it simple for us to share and modify the database schema for the application. up() and down() are two methods in a migration file.

The up() method creates new databases, tables, columns, or indexes, whereas the down() method is used to undo the up method's actions.

Laravel uses migrations to create database schemas easily. We keep track of which tables to create, update, and delete in migration files.

Each file is stored with its creation timestamp to keep track of the order in which migration files were created. Anyone who clones your project can run "PHP artisan migrate" to run those migrations to create the database in their environment as migrations are updated along with your code in GitHub, GitLab, etc. The example provided above is how a typical migration file appears.

When we run php artisan migrate, the up() method also runs, and when we run php artisan migrate:rollback, it runs the down() method.

Only the previously executed migration is rolled back if we do a rollback.

Moreover, you can run php artisan migrate:reset if you want to undo all migrations.

You can first use php artisan migrate:refresh to roll back and restart migrations, and php artisan migrate:fresh to drop the tables and then restart migrations.

In Laravel, seeders are used to insert data into database tables automatically. To run the seeder, we can run the php artisan db:seed command and populate the database tables after running migrations to create the tables.

Using the artisan command listed below, we can create a new Seeder:

php artisan make:seeder [className]

Here is an example of a seeder:

<?php

use App\Models\Auth\User;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Seeder;

class UserTableSeeder extends Seeder
{
    /**
     * Run the database seeds.
     */
    public function run()
    {
        factory(User::class, 10)->create();
    }
}

Note that the run() method in the code above will create 10 new users using the User factory.

Note: Commonly asked Laravel interview question.

When a data row is deleted from the database using any method, we do not actually delete the data; instead, we add a timestamp of the deletion.

We can add soft delete features by including a trait like the one in the model file:

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Post extends Model {

    use SoftDeletes;

    protected $table = 'posts';

    // ...
}

In Laravel, request validation can be carried out using the controller method or by building a class that contains the validation guidelines and error messages.

Here is an example of request validation in Laravel:

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

    // The blog post is valid...
}

Laravel's command-line tool for assisting developers in creating applications is called Artisan. Artisan can use the ‘make’ command to assist in creating the files. The following is a list of some useful make commands:

• php artisan make:controller - Make Controller file
• php artisan make:model - Make a Model file
• php artisan make:migration - Make Migration file
• php artisan make:seeder - Make Seeder file
• php artisan make:factory - Make Factory file
• php artisan make:policy - Make Policy file
• php artisan make:command - Make a new artisan command

Note: Commonly asked Laravel interview question.

Laravel is perhaps the best option for creating advanced, scalable full-stack web applications. Laravel can be used for the backend of full-stack web applications, and blade files or SPAs using Vue.js, which is included by default, can be used for the frontend. However, it can also be used to give an SPA application access to the Rest APIs simply.

Therefore, Laravel can be used to create backend-only APIs or full-stack applications.

Packages and Bundles are both terms used in Laravel. The main means of expanding Laravel's functionality is through packages. A complete BDD testing framework like Behat or a great way to work with dates like Carbon are just two examples of packages. Additionally, Laravel supports the development of unique packages.

Different packages come in various varieties. They come in standalone packages in some cases. They are therefore compatible with all PHP frameworks. Examples of standalone packages are frameworks like Carbon and Behat. In addition, Laravel can be used with other packages. Routes, controllers, views, and configurations that are primarily made to improve a Laravel application may be found in these packages.

Service providers are the main location where all Laravel applications are configured—using service providers, Laravel bootstraps both applications and its core services. These are effective tools for performing dependency injection and maintaining class dependencies. Additionally, service providers give Laravel instructions on how to bind different components to the Laravel Service Container.

The following artisan command can be used to create a service provider:

php artisan make: provider ClientsServiceProvider  

Almost all service providers extend the Illuminate\Support\Service\Providerclass. Most service providers have the following features in their files:

1. Register() Function
2. Boot() Function

Only bind items into the service contained within the Register() method. The Register() method should never be used to register any event listeners, routes, or other functionality.

One of the key components of the Laravel framework is the Eloquent ORM (Object-Relational Mapping) library. It could be described as a more sophisticated active record pattern implementation in PHP.

An architectural pattern called the "active record pattern" can be found in software. It is in charge of maintaining object data stored in relational databases in memory.

In addition to imposing restrictions on the relationships between database objects, Eloquent ORM is also in charge of providing the internal methods.Following the active record pattern, Eloquent ORM represents database tables as classes with object instances bound to specific table rows.

Note: Commonly asked Laravel interview question.