Composer: PHP Package Management

Composer Basics

What is Composer?

Composer is the dependency manager for PHP. It manages packages (libraries) your project needs.

Project (your Magento store)
  |
  +-- vendor/           (auto-generated)
  |     +-- autoload.php
  |     +-- magento/
  |     +-- psr/
  +-- composer.json      (your configuration)
  +-- composer.lock      (locked versions)

composer.json

{
    "name": "vendor/module-name",
    "description": "A custom Magento 2 module",
    "type": "magento2-module",
    "version": "1.0.0",
    "license": "proprietary",
    "require": {
        "php": ">=8.1",
        "magento/framework": "^103.0",
        "magento/module-catalog": "^103.0"
    },
    "require-dev": {
        "phpunit/phpunit": "^9.5",
        "squizlabs/php_codesniffer": "^3.7"
    },
    "autoload": {
        "psr-4": {
            "Vendor\\Module\\": ""
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Vendor\\Module\\Test\\": "Test/"
        }
    }
}

Key Sections

Section	Purpose
require	Production dependencies
require-dev	Development dependencies
autoload	How to load classes
autoload-dev	Autoloading for tests
scripts	Custom commands
extra	Package-specific config
repositories	Custom package sources

Composer Commands

# Install dependencies (from composer.lock)
composer install

# Update dependencies (updates composer.lock)
composer update

# Add a new dependency
composer require vendor/package-name:^2.0

# Remove a dependency
composer remove vendor/package-name

# Update a specific package
composer update vendor/package-name

# Show installed packages
composer show

# Show outdated packages
composer outdated

# Dump autoloader (after adding classes)
composer dump-autoload

# Validate composer.json
composer validate

Version Constraints

^2.0      >=2.0.0 <3.0.0 (semver compatible)
^2.3.1    >=2.3.1 <3.0.0
~2.3      >=2.3.0 <2.4.0 (next minor)
~2.3.1    >=2.3.1 <2.4.0
*         Any version
>=2.0     At least 2.0
2.0.*     Any 2.0.x version

Key Takeaway

Composer manages PHP dependencies. composer.json defines what you need, composer.lock locks exact versions. Use ^ for semver compatibility, ~ for minor version limits.

Autoloading and Scripts

PSR-4 Autoloading

{
    "autoload": {
        "psr-4": {
            "Vendor\\Module\\": "src/"
        }
    }
}

This maps Vendor\Module\ namespace to src/ directory:

Vendor\Module\Product  ->  src/Product.php
Vendor\Module\Helper\Data  ->  src/Helper/Data.php

Multiple Namespaces

{
    "autoload": {
        "psr-4": {
            "Vendor\\Module\\": "",
            "Vendor\\Module\\Test\\": "Test/"
        }
    }
}

Classmap Autoloading

{
    "autoload": {
        "classmap": [
            "src/",
            "lib/"
        ]
    }
}

Files Autoloading

{
    "autoload": {
        "files": [
            "src/helpers.php",
            "src/constants.php"
        ]
    }
}

Scripts

{
    "scripts": {
        "pre-install-cmd": "echo 'About to install...'",
        "post-install-cmd": [
            "@php bin/magento setup:upgrade",
            "@php bin/magento cache:clean"
        ],
        "pre-update-cmd": "echo 'About to update...'",
        "post-update-cmd": "@php bin/magento setup:upgrade",
        "post-root-package-install": "@php bin/magento setup:di:compile",
        "test": "phpunit",
        "lint": "phpcs --standard=PSR12 src/",
        "format": "phpcbf --standard=PSR12 src/"
    }
}

Composer Scripts for Magento

{
    "scripts": {
        "agento-setup": [
            "@php bin/magento setup:upgrade",
            "@php bin/magento setup:di:compile",
            "@php bin/magento setup:static-content:deploy -f",
            "@php bin/magento cache:clean"
        ],
        "agento-reinstall": [
            "@php bin/magento setup:install --force",
            "@agento-setup"
        ]
    }
}

Key Takeaway

Composer's autoload section maps namespaces to directories. Scripts automate setup tasks. Use classmap for non-PSR-4 classes and files for helper functions.

Magento's composer.json

Magento Root composer.json

{
    "name": "magento/project-community-edition",
    "description": "Magento Community Edition",
    "type": "project",
    "license": "proprietary",
    "require": {
        "php": ">=8.1",
        "magento/framework": "^103.0",
        "magento/module-backend": "^103.0",
        "magento/module-catalog": "^103.0",
        "magento/module-customer": "^103.0",
        "magento/module-sales": "^103.0"
    },
    "autoload": {
        "psr-4": {
            "Magento\\\\": "app/code/Magento/",
            "": "app/code/"
        }
    },
    "config": {
        "sort-packages": true,
        "preferred-install": "dist"
    },
    "extra": {
        "magento-force": "override"
    }
}

Custom Module composer.json

{
    "name": "vendor/module-name",
    "description": "Custom module for specific functionality",
    "type": "magento2-module",
    "version": "1.0.0",
    "license": "proprietary",
    "require": {
        "php": ">=8.1",
        "magento/framework": "^103.0",
        "magento/module-catalog": "^103.0",
        "magento/module-customer": "^103.0"
    },
    "require-dev": {
        "phpunit/phpunit": "^9.5",
        "squizlabs/php_codesniffer": "^3.7"
    },
    "autoload": {
        "psr-4": {
            "Vendor\\Module\\": ""
        },
        "files": [
            "registration.php"
        ]
    },
    "autoload-dev": {
        "psr-4": {
            "Vendor\\Module\\Test\\Unit\\": "Test/Unit/",
            "Vendor\\Module\\Test\\Integration\\": "Test/Integration/"
        }
    },
    "extra": {
        "magento-core-composer-plugin": true,
        "force": "override"
    },
    "config": {
        "sort-packages": true
    }
}

Installing a Custom Module via Composer

# From private repository
composer require vendor/module-name:@stable

# From local path (for development)
composer config repositories.local path /path/to/module
composer require vendor/module-name:@dev

# From Git repository
composer config repositories.vcs https://github.com/vendor/module.git
composer require vendor/module-name:dev-main

Magento Module Installation Flow

1. composer require vendor/module
   -> Downloads module to vendor/vendor/module

2. composer.json autoload maps namespace
   -> Vendor\Module\ -> vendor/vendor/module/

3. registration.php registers module
   -> ComponentRegistrar::register(MODULE, 'Vendor_Module', ...)

4. bin/magento setup:upgrade
   -> Reads module.xml, db_schema.xml
   -> Creates/updates database tables

5. bin/magento setup:di:compile
   -> Generates dependency injection code
   -> Creates proxy and factory classes

Key Takeaway

Magento modules follow a specific composer.json structure with type 'magento2-module'. Registration happens through both composer.json autoload and registration.php. Always run setup:upgrade after installing new modules.

Flashcards

Question

What is composer.json?

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Answer

The configuration file that defines your project's dependencies, autoloading rules, scripts, and other metadata. Read by Composer to manage packages.

Question

What is composer.lock?

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Answer

Locks exact versions of all installed dependencies. Ensures consistent installations across environments. Generated by composer update.

Question

What does ^2.0 version constraint mean?

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Answer

Greater than or equal to 2.0.0, less than 3.0.0. Semver compatible - allows updates within the same major version.

Question

What does composer require do?

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Answer

Adds a new dependency to composer.json and installs it. Example: composer require vendor/package:^2.0

Question

What is the type field in Magento composer.json?

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Answer

magento2-module - identifies the package as a Magento module that should be managed by the Magento framework.

Question

What autoload section does a Magento module use?

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Answer

PSR-4: maps the module's namespace to its root directory. Example: "Vendor\\Module\\": "" maps to the module's root.

Question

What scripts can you define in composer.json?

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Answer

pre-install-cmd, post-install-cmd, pre-update-cmd, post-update-cmd, and custom scripts. Used for setup automation.

Question

What is the preferred-install config option?

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Answer

dist: downloads zip archive (faster). source: clones git repository (better for development). Default is dist.

Revision Notes

Key Takeaways

1. composer.json defines dependencies, autoloading, and scripts
2. composer.lock locks exact versions for consistent installations
3. ^2.0 means >=2.0.0 <3.0.0 (semver compatible)
4. composer install reads lock file, composer update resolves new versions
5. Magento modules use type: 'magento2-module'
6. Always run setup:upgrade after installing new modules
7. dump-autoload regenerates autoloader without updating packages

Interview Tips

• Explain the difference between composer install and update
• Know version constraint syntax (^, ~, >=, *)
• Describe how Magento modules are installed via Composer
• Understand the autoload section (PSR-4, classmap, files)
• Know the setup:upgrade and setup:di:compile commands

Cheat Sheet

Composer Cheat Sheet

Commands:
composer install - Install from lock file
composer update - Update packages
composer require pkg:^2 - Add dependency
composer remove pkg - Remove dependency
dump-autoload - Regenerate autoloader

Version Constraints:
^2.0 >=2.0.0 <3.0.0
~2.3 >=2.3.0 <2.4.0

```
  Any version
```

=2.0 At least 2.0

Magento Module:

{
  "type": "magento2-module",
  "autoload": {
    "psr-4": { "Vendor\\Module\\": "" },
    "files": ["registration.php"]
  }
}

Post-Install:
bin/magento setup:upgrade
bin/magento setup:di:compile
bin/magento cache:clean

Composer Basics

What is Composer?

composer.json

Key Sections

Composer Commands

Version Constraints

Key Takeaway

Autoloading and Scripts

PSR-4 Autoloading

Multiple Namespaces

Classmap Autoloading

Files Autoloading

Scripts

Composer Scripts for Magento

Key Takeaway

Magento's composer.json

Magento Root composer.json

Custom Module composer.json

Installing a Custom Module via Composer

Magento Module Installation Flow

Key Takeaway

Quiz

Flashcards

Revision Notes

Key Takeaways

Interview Tips

Cheat Sheet

Composer Cheat Sheet