Best Laravel Interview Guide

Laravel Interview Questions (Answered) You Should Know

Laravel is a web framework for making custom applications. It runs on PHP and is entirely free and open source. We'll discuss what makes this framework a good choice and why you want to base your app on it.

What is the Laravel?

Laravel is a free, open-source PHP web framework created by Taylor Otwell and intended to develop web applications following the modelโ€“viewโ€“controller (MVC) architectural pattern.

๐Ÿ”— source: codingcompiler.com

What are some benefits of Laravel over other Php frameworks?

  • The setup and customization process is easy and fast as compared to others.
  • Inbuilt Authentication System
  • Supports multiple file systems
  • Pre-loaded packages like Laravel Socialite, Laravel cashier, Laravel elixir, Passport, Laravel Scout
  • Eloquent ORM (Object Relation Mapping) with PHP active record implementation
  • Built-in command-line tool "Artisan" for creating a code skeleton, database structure and build their migration

๐Ÿ”— source: mytectra.com

Explain Migrations in Laravel

Laravel Migrations are like version control for the database, allowing a team to modify and share the application's database schema easily. Migrations are typically paired with Laravel's schema builder to build the application's database schema quickly.

๐Ÿ”— source: laravelinterviewquestions.com

What is the Facade Pattern used for?

Facades provide a static interface to classes that are available in the application's service container. Laravel facades serve as static proxies to underlying classes in the service container, providing the benefit of a terse, expressive syntax while maintaining more testability and flexibility than traditional static methods.

All of Laravel's facades are defined in the Illuminate\Support\Facades namespace.
Consider:

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

๐Ÿ”— source: laravel.com

What is Service Container?

The Laravel service container is a tool for managing class dependencies and performing dependency injection.

๐Ÿ”— source: laravel.com

What are Eloquent Models?

The Eloquent ORM included with Laravel provides a beautiful, simple ActiveRecord implementation for working with your database. Each database table has a corresponding Model, which is used to interact with that table. Models allow you to query for data in your tables and insert new records into the table.

๐Ÿ”— source: laravel.com

What are Laravel events?

Laravel event provides a simple observer pattern implementation that allows to subscribe and listen for events in the application. An event is an incident or occurrence detected and handled by the program.

Below are some events examples in Laravel:

  • A new user has registered
  • A new comment is posted
  • User login/logout
  • The new product is added.

๐Ÿ”— source: mytectra.com

What do you know about query builder in Laravel?

Laravel's database query builder provides a convenient, fluent interface to creating and running database queries. It can perform most database operations in your application and works on all supported database systems.

The Laravel query builder uses PDO parameter binding to protect your application against SQL injection attacks. There is no need to clean strings being passed as bindings.

Some QB features:

  • Chunking
  • Aggregates
  • Selects
  • Raw Expressions
  • Joins
  • Unions
  • Where
  • Ordering, Grouping, Limit, & Offset

๐Ÿ”— source: laravel.com

How do you generate migrations?

Migrations are like version control for your database, allowing your team to modify and share the application's database schema easily. Migrations are typically paired with Laravel's schema builder to build your application's database schema quickly.

To create a migration, use the make:migration Artisan command:

php artisan make:migration create_users_table

The new migration will be placed in your database/migrations directory. Each migration file name contains a timestamp which allows Laravel to determine the order of the migrations.

๐Ÿ”— source: laravel.com

How do you mock static facade methods?

Facades provide a "static" interface to classes that are available in the application's service container. Unlike traditional static method calls, facades may be mocked. We can mock the call to the static facade method using the shouldReceive method, which will return an instance of a Mockery mock.

// actual code
$value = Cache::get('key');
// testing
Cache::shouldReceive('get')
->once()
->with('key')
->andReturn('value');

๐Ÿ”— source: laravel.com

What is the benefit of eager loading? When do you use it?

When accessing Eloquent relationships as properties, the relationship data is "lazy loaded." This means the relationship data is not loaded until you first access the property. However, Eloquent can "eager load" relationships at the time you query the parent model.

Eager loading alleviates the N + 1 query problem when we have nested objects (like books -> author). We can use eager loading to reduce this operation to just two queries.

๐Ÿ”— Source: FullStack.Cafe

How do you do soft deletes?

Scopes allow you to reuse query logic in your models easily. To define a scope, prefix a model method with scope:

class User extends Model {
public function scopePopular($query)
{
return $query->where('votes', '>', 100);
}
public function scopeWomen($query)
{
return $query->whereGender('W');
}
}

Usage:

$users = User::popular()->women()->orderBy('created_at')->get();

Sometimes you may wish to define a scope that accepts parameters. Dynamic scopes accept query parameters:

class User extends Model {
public function scopeOfType($query, $type)
{
return $query->whereType($type);
}
}

Usage:

$users = User::ofType('member')->get();

๐Ÿ”— source: laravel.com

What are named routes in Laravel?

Named routes allow referring to routes when generating redirects or Url's more comfortably. You can specify named routes by chaining the name method onto the route definition:

Route::get('user/profile', function () {
//
})->name('profile');

You can specify route names for controller actions:

Route::get('user/profile', 'UserController@showProfile')->name('profile');

Once you have assigned a name to your routes, you may use the route's name when generating URLs or redirects via the global route function:

// Generating URLs...
$url = route('profile');
// Generating Redirects...
return redirect()->route('profile');

๐Ÿ”— source: laravelinterviewquestions.com

What is Closure in Laravel?

A Closure is an anonymous function. Closures are often used as callback methods and can be used as a parameter in a function.

function handle(Closure $closure) {
$closure('Hello World!');
}
handle(function($value){
echo $value;
});

๐Ÿ”— source: stackoverflow.com

List some Aggregates methods provided by query builder in Laravel?

An aggregate function is a function where the values of multiple rows are grouped as input on specific criteria to form a single value of more significant meaning or measurements such as a set, a bag, or a list.

Below is list of some Aggregates methods provided by Laravel query builder:

  • count()
$products = DB::table(โ€˜productsโ€™)->count();
  • max()
$price = DB::table(โ€˜ordersโ€™)->max(โ€˜priceโ€™);
  • min()
$price = DB::table(โ€˜ordersโ€™)->min(โ€˜priceโ€™);
  • avg()
*$price = DB::table(โ€˜ordersโ€™)->avg(โ€˜priceโ€™);
  • sum()
$price = DB::table(โ€˜ordersโ€™)->sum(โ€˜priceโ€™);

๐Ÿ”— Source: laravelinterviewquestions.com

What is reverse routing in Laravel?

In Laravel, reverse routing is generating URLs based on route declarations. Reverse routing makes your application so much more flexible. For example, the below route declaration tells Laravel to execute the action "login" in the user's controller when the request's URI is 'login.'

http://mysite.com/login

Route::get(โ€˜loginโ€™, โ€˜users@loginโ€™);

Using reverse routing, we can create a link to it and pass in any parameters that we have defined. Optional parameters, if not supplied, are removed from the generated link.

{{ HTML::link_to_action('users@login') }}

It will create a link like http://mysite.com/login in view.

๐Ÿ”— source: stackoverflow.com

Let's create Enumerations for PHP. Prove some code examples. And what if our code requires more validation of enumeration constants and values?

Depending upon the use case, I would typically use something simple like the following:

abstract class DaysOfWeek
{
const Sunday = 0;
const Monday = 1;
// etc.
}
$today = DaysOfWeek::Sunday;

Here's an expanded example that may better serve a much more comprehensive range of cases:

abstract class BasicEnum {
private static $constCacheArray = NULL;
private static function getConstants() {
if (self::$constCacheArray == NULL) {
self::$constCacheArray = [];
}
$calledClass = get_called_class();
if (!array_key_exists($calledClass, self::$constCacheArray)) {
$reflect = new ReflectionClass($calledClass);
self::$constCacheArray[$calledClass] = $reflect - > getConstants();
}
return self::$constCacheArray[$calledClass];
}
public static function isValidName($name, $strict = false) {
$constants = self::getConstants();
if ($strict) {
return array_key_exists($name, $constants);
}
$keys = array_map('strtolower', array_keys($constants));
return in_array(strtolower($name), $keys);
}
public static function isValidValue($value, $strict = true) {
$values = array_values(self::getConstants());
return in_array($value, $values, $strict);
}
}

And we could use it as:

abstract class DaysOfWeek extends BasicEnum {
const Sunday = 0;
const Monday = 1;
const Tuesday = 2;
const Wednesday = 3;
const Thursday = 4;
const Friday = 5;
const Saturday = 6;
}
DaysOfWeek::isValidName('Humpday'); // false
DaysOfWeek::isValidName('Monday'); // true
DaysOfWeek::isValidName('monday'); // true
DaysOfWeek::isValidName('monday', $strict = true); // false
DaysOfWeek::isValidName(0); // false
DaysOfWeek::isValidValue(0); // true
DaysOfWeek::isValidValue(5); // true
DaysOfWeek::isValidValue(7); // false
DaysOfWeek::isValidValue('Friday'); // false

๐Ÿ”— source: stackoverflow.com

What are autoloading classes in PHP?

PHP allows the last chance to load the class or interface before it fails with an error with autoloaders.

The spl_autoload_register() function in PHP can register any number of autoloaders, enable classes and interfaces to autoload even if they are undefined.

spl_autoload_register(function ($classname) {
include $classname . '.php';
});
$object = new Class1();
$object2 = new Class2();

In the above example, we do not need to include Class1.php and Class2.php. The spl_autoload_register() function will automatically load Class1.php and Class2.php.

๐Ÿ”— source: github.com/Bootsity

Does PHP support method overloading?

Method overloading is the phenomenon of using the same method name with different signatures. You cannot overload PHP functions, and function signatures are based only on their names and do not include argument lists, so you cannot have two functions with the same name.

You can, however, declare a variadic function that takes in a variable number of arguments. You would use func_num_args() and func_get_arg() to get the arguments passed and use them usually.

function myFunc() {
for ($i = 0; $i < func_num_args(); $i++) {
printf("Argument %d: %s\n", $i, func_get_arg($i));
}
}
/*
Argument 0: a
Argument 1: 2
Argument 2: 3.5
*/
myFunc('a', 2, 3.5);

๐Ÿ”— source: github.com/Bootsity

Why do we need Traits in Laravel?

Traits have been added to PHP for a straightforward reason: PHP does not support multiple inheritances. Simply put, a class cannot extend more than one class at a time. This becomes laborious when you need functionality declared in two different classes used by other classes as well. The result is that you would have to repeat code to get the job done without tangling yourself up in a mist of cobwebs.

Enter traits. These allow us to declare a type of class that contains methods that can be reused. Better still, their methods can be directly injected into any class you use, and you can use multiple traits in the same class. Let's look at a simple Hello World example.

trait SayHello
{
private function hello()
{
return "Hello ";
}
private function world()
{
return "World";
}
}
trait Talk
{
private function speak()
{
echo $this->hello() . $this->world();
}
}
class HelloWorld
{
use SayHello;
use Talk;
public function __construct()
{
$this->speak();
}
}
$message = new HelloWorld(); // returns "Hello World";

๐Ÿ”— source: conetix.com.au

What is Autoloader in PHP?

Autoloaders define ways to automatically include PHP classes in your code without using statements like require and include.

  • PSR-4 would allow for more superficial folder structures but would prevent us from knowing the exact path of a class just by looking at the fully qualified name.
  • PSR-0, on the other hand, is chaotic on the hard drive but supports developers who are stuck in the past (the underscore-in-class-name users) and helps us discern the location of a class just by looking at its name.

๐Ÿ”— source: sitepoint.com

What does yield mean in PHP?

Explain this code and what it yield does:

function a($items) {
foreach ($items as $item) {
yield $item + 1;
}
}

The yield Keyword returns data from a generator function. A generator function is effectively a more compact and efficient way to write an Iterator. It allows you to define a function that will calculate and return values while looping over it.

So the function in the question is almost the same as this one without:

function b($items) {
$result = [];
foreach ($items as $item) {
$result[] = $item + 1;
}
return $result;
}

With only one difference that a() returns a generator andb() just a simple array. You can iterate on both.

The generator version of the function does not allocate an entire array and is, therefore, less memory-demanding. Generators can be used to work around memory limits. Because generators compute their yielded values only on-demand, they help represent sequences that would be expensive or impossible to compute at once.

๐Ÿ”— source: stackoverflow.com

What does a $$$ mean in PHP?

A syntax such as $$variable is called Variable Variable. Let's give them $$$ a try:

$real_variable = 'test';
$name = 'real_variable'; // variable variable for real variable
$name_of_name = 'name'; // variable variable for variable variable
echo $name_of_name . '<br />';
echo $$name_of_name . '<br />';
echo $$$name_of_name . '<br />';

And here's the output :

name
real_variable
test

๐Ÿ”— Source: guru99.com

Good luck!

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