Dependency injection concept in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to inject the Logger dependency into the UserService constructor.

PHP

<?php
class UserService {
    private $logger;
    public function __construct([1] $logger) {
        $this->logger = $logger;
    }
}

Drag options to blanks, or click blank then click option'

ALogger

BUserService

CDatabase

DConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong class name in the constructor parameter.

Not specifying a type for the constructor parameter.

The constructor requires an instance of the Logger class to be injected. This is dependency injection.

2fill in blank

medium

Complete the code to create a new UserService instance with a Logger injected.

PHP

<?php
$logger = new [1]();
$userService = new UserService($logger);

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AUserService

BLogger

CDatabase

DConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Creating the wrong class instance.

Not creating an instance before injecting.

You must create a Logger object to inject it into UserService.

3fill in blank

hard

Fix the error in the constructor to properly assign the injected dependency.

PHP

<?php
class UserService {
    private $logger;
    public function __construct(Logger $logger) {
        $this->[1] = $logger;
    }
}

Drag options to blanks, or click blank then click option'

Alog

BlogService

Clogger

DLogger

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different property name than declared.

Using uppercase or incorrect casing.

The property name is $logger, so assign to $this->logger.

4fill in blank

hard

Fill both blanks to complete the setter method for dependency injection.

PHP

<?php
class UserService {
    private $logger;
    public function [1](Logger $logger) {
        $this->[2] = $logger;
    }
}

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AsetLogger

BgetLogger

Clogger

Dlog

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' instead of 'set' for the method name.

Assigning to a wrong property name.

The setter method is named setLogger and assigns to the property $logger.

5fill in blank

hard

Fill all three blanks to complete the code that uses dependency injection with interface and implementation.

PHP

<?php
interface LoggerInterface {
    public function log(string $message);
}

class FileLogger implements [1] {
    public function log(string $message) {
        // write to file
    }
}

class UserService {
    private $logger;
    public function __construct([2] $logger) {
        $this->logger = $logger;
    }
    public function doAction() {
        $this->logger->[3]("Action done");
    }
}

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ALoggerInterface

Clog

Dwrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using the implementation class name instead of interface in constructor.

Calling a method name that does not exist.

The class FileLogger implements LoggerInterface. The constructor type hints LoggerInterface. The method called is log.