PHP Composer

What is Composer in PHP?

Composer is a dependency manager for PHP. It allows you to easily install, update, and manage third-party libraries in your PHP projects. Composer has become a standard tool for modern PHP development.

Why Use Composer?

• Manages project dependencies automatically

• Avoids manual library downloads

• Handles version conflicts

• Provides autoloading (PSR standards)

• Essential for frameworks like Laravel, Symfony, and CodeIgniter 4

Installing Composer

Step 1: Check PHP Version

php -v

Step 2: Install Composer (Windows / Linux / macOS)

composer --version

If not installed, download from getcomposer.org

Creating a New Composer Project

composer init

This creates a composer.json file.

composer.json File (Example)

{
  "name": "quizer/demo",
  "description": "Demo PHP project",
  "require": {
    "monolog/monolog": "^3.0"
  }
}

Installing Dependencies

composer install

This will:

• Download libraries

• Create vendor/ folder

• Generate composer.lock

Adding a Package

composer require monolog/monolog

Updating Dependencies

composer update

Removing a Package

composer remove monolog/monolog

Autoloading with Composer

Include Autoload File

require 'vendor/autoload.php';

Using Installed Package

use Monolog\Logger;
use Monolog\Handler\StreamHandler;

$log = new Logger('app');
$log->pushHandler(new StreamHandler('app.log'));
$log->info('Composer is working!');

PSR-4 Autoloading

Add to composer.json:

"autoload": {
  "psr-4": {
    "App\\": "src/"
  }
}

Run:

composer dump-autoload

composer.lock File

• Locks exact versions

• Ensures same versions across environments

• Should be committed to version control

Common Composer Commands

Best Practices

• Commit composer.json and composer.lock

• Do not commit vendor/ folder

• Use version constraints wisely

• Update dependencies regularly

Common Use Cases

• Installing libraries (PDF, JWT, Logger)

• Framework development

• Package management

• Autoloading classes

Conclusion

Composer is an essential tool for modern PHP development. It simplifies dependency management, improves project structure, and enables the use of powerful third-party libraries.