Dependency injection in controllers in Laravel - Mini Project: Build & Apply

Dependency Injection in Laravel Controllers

📖 Scenario: You are building a simple Laravel web application that manages books. You want to use dependency injection in a controller to get a service that handles book data.

🎯 Goal: Create a Laravel controller that uses dependency injection to receive a BookService instance. This service will provide a method to get all books. You will set up the service, inject it into the controller, and call its method.

📋 What You'll Learn

Create a BookService class with a method getAllBooks() that returns an array of book titles.

Create a controller named BookController.

Inject the BookService into the BookController constructor using dependency injection.

Use the injected BookService inside a method index() in the controller to get all books.

💡 Why This Matters

🌍 Real World

Dependency injection is a common pattern in Laravel to manage class dependencies cleanly. It helps you write modular and testable code.

💼 Career

Understanding dependency injection in controllers is essential for Laravel developers. It is widely used in professional Laravel projects to manage services and repositories.

1

Create the BookService class

Create a class called BookService with a public method getAllBooks() that returns an array with these exact book titles: 'The Hobbit', '1984', and 'Pride and Prejudice'.

Laravel

# Create the BookService class with getAllBooks method
# Your code here

Need a hint?

Define a class named BookService inside the App\Services namespace. Add a public method getAllBooks() that returns the array of book titles.

2

Create the BookController with constructor injection

Create a controller class called BookController inside the App\Http\Controllers namespace. Add a constructor that accepts a BookService parameter and stores it in a private property called bookService.

Laravel

<?php

namespace App\Services;

class BookService
{
    public function getAllBooks(): array
    {
        return ['The Hobbit', '1984', 'Pride and Prejudice'];
    }
}

// Create BookController with constructor injection
# Your code here

Need a hint?

Remember to import BookService with a use statement. Define a private property bookService and assign the injected service to it in the constructor.

3

Add the index method to use the injected service

Inside the BookController class, add a public method called index(). Inside this method, call $this->bookService->getAllBooks() and store the result in a variable called books.

Laravel

bookService = $bookService;
    }

    // Add index method here
    # Your code here
}

Need a hint?

Define the index() method to call the service method and return the list of books.

4

Complete the controller with namespace and use statements

Ensure the BookController class has the correct namespace App\Http\Controllers and includes the use App\Services\BookService; statement at the top. Confirm the full controller code includes the constructor and index() method using dependency injection.

Laravel

<?php

namespace App\Services;

class BookService
{
    public function getAllBooks(): array
    {
        return ['The Hobbit', '1984', 'Pride and Prejudice'];
    }
}

// Confirm the full BookController code with namespace and use statements
# Your code here

Need a hint?

Make sure the controller file starts with the correct namespace and imports the BookService. The class should have the constructor and index() method as before.