### Install Magento Coding Standard via Git Clone

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Install the Magento Coding Standard for development by cloning the GitHub repository and running Composer install.

```bash
git clone git@github.com:magento/magento-coding-standard.git
cd magento-coding-standard
composer install
```

--------------------------------

### Install ESLint Dependencies

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Install all necessary Node.js packages for ESLint as described in the package.json file.

```bash
npm install
```

--------------------------------

### PHPCBF Auto-Fixing Summary Example

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Example output summarizing the results of PHPCBF auto-fixing, showing the number of errors fixed and remaining for each file.

```text
PHPCBF RESULT SUMMARY
----------------------------------------------------------------------
FILE                                                  FIXED  REMAINING
----------------------------------------------------------------------
app/code/MyVendor/MyExtension/view/frontend/templates/mytemplate.phtml
                                                      3      0
----------------------------------------------------------------------
A TOTAL OF 3 ERRORS WERE FIXED IN 1 FILE
----------------------------------------------------------------------
```

--------------------------------

### Verify Magento Coding Standard Installation

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Verify that the Magento Coding Standard is installed and recognized by PHP_CodeSniffer.

```bash
vendor/bin/phpcs -i
```

--------------------------------

### Example: Run Rector PHP for Magento CMS Model

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

An example of running Rector PHP to process the Magento CMS Model directory, including the autoload file.

```bash
vendor/bin/rector process magento2ce/app/code/Magento/Cms/Model --dry-run --autoload-file magento2ce/vendor/autoload.php
```

--------------------------------

### Install Magento Coding Standard with Composer

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Install the Magento Coding Standard as a development dependency in your Magento 2 project using Composer.

```bash
composer require --dev magento/magento-coding-standard
```

--------------------------------

### Install Node.js Dependencies for ESLint

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Installs necessary Node.js dependencies for using ESLint with Magento coding standards. This is a prerequisite for running ESLint.

```bash
# Install Node.js dependencies
npm install
```

--------------------------------

### PHPCS Violation Output Example

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Example output format for violations detected by PHP_CodeSniffer using the Magento2 standard, indicating file, severity, and sniff type.

```text
FILE: app/code/MyVendor/MyExtension/Model/MyModel.php
--------------------------------------------------------------------------------
FOUND 2 ERRORS AND 1 WARNING AFFECTING 3 LINES
--------------------------------------------------------------------------------
 10 | ERROR   | [x] Possible raw SQL statement detected (Magento2.SQL.RawQuery)
 25 | ERROR   | [ ] Use of eval() is forbidden (Squiz.PHP.Eval)
 30 | WARNING | [x] Use of $this in templates is deprecated (Magento2.Templates.ThisInTemplate)
--------------------------------------------------------------------------------
```

--------------------------------

### Configure PHP_CodeSniffer for Magento Standard

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Add the Magento standard path to your project's composer.json to enable automatic configuration after installation or updates.

```json
{
"scripts": {
  "post-install-cmd": [
    "([ $COMPOSER_DEV_MODE -eq 0 ] || vendor/bin/phpcs --config-set installed_paths ../../magento/magento-coding-standard/)"
  ],
  "post-update-cmd": [
    "([ $COMPOSER_DEV_MODE -eq 0 ] || vendor/bin/phpcs --config-set installed_paths ../../magento/magento-coding-standard/)"
]
}
}
```

--------------------------------

### Detect Unescaped Output in PHTML Templates (XSS)

Source: https://context7.com/magento/magento-coding-standard/llms.txt

This PHP code demonstrates examples of unescaped output in PHTML templates that trigger the Magento2.Security.XssTemplate.FoundUnescaped sniff, and shows correctly escaped alternatives.

```php
<?php
// BAD: Unescaped output - will trigger Magento2.Security.XssTemplate.FoundUnescaped
echo $block->getData('user_input');
echo $variable;
echo $block->getCustomValue();

// GOOD: Properly escaped output using Magento escape methods
echo $block->escapeHtml($block->getData('user_input'));
echo $block->escapeUrl($url);
echo $block->escapeJs($javascriptValue);
echo $block->escapeQuote($attributeValue);
echo $block->escapeXssInUrl($untrustedUrl);
echo $block->escapeCss($cssValue);

// GOOD: Methods containing 'html' in name are considered safe
echo $block->toHtml();
echo $block->getChildHtml('child.block');
echo $block->renderHtmlContent();

// GOOD: Using @noEscape annotation for intentionally unescaped output
/** @noEscape */ echo $block->getTrustedHtmlContent();
?>
```

--------------------------------

### Create Standalone Magento Coding Standard Project

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Create a standalone project for the Magento Coding Standard using Composer create-project.

```bash
composer create-project magento/magento-coding-standard --stability=dev magento-coding-standard
```

--------------------------------

### Run Unit Tests for Coding Standard Rules

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Execute unit tests to verify the correctness of the coding standard rules using PHPUnit.

```bash
vendor/bin/phpunit
```

--------------------------------

### Execute ESLint for Code Analysis

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Run ESLint to analyze JavaScript code in a specified path.

```bash
npm run eslint -- path/to/analyze
```

--------------------------------

### Run PHPUnit Tests with Coverage Report

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Execute PHPUnit tests and generate an HTML coverage report to analyze test coverage.

```bash
vendor/bin/phpunit --coverage-html coverage/
```

--------------------------------

### Run ESLint on Specific Directory

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Execute ESLint to check JavaScript code quality in a specified directory.

```bash
npm run eslint -- pub/static/frontend/Magento/luma/en_US/js
```

--------------------------------

### Magento ESLint Configuration

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Configuration file for Magento ESLint, extending base configurations and including Magento-specific plugins.

```javascript
// eslint.config.mjs - Magento ESLint configuration
import { defineConfig } from "eslint/config";
import magentoCodingStandardEslintPlugin from "magento-coding-standard-eslint-plugin";
import path from "node:path";
import { fileURLToPath } from "node:url";
import js from "@eslint/js";
import { FlatCompat } from "@eslint/eslintrc";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const compat = new FlatCompat({
    baseDirectory: __dirname,
    recommendedConfig: js.configs.recommended,
    allConfig: js.configs.all
});

export default defineConfig([
    {
        extends: compat.extends(
            "./.eslintrc-reset",    // Reset all rules
            "./.eslintrc-magento",  // Magento standards
            "./.eslintrc-jquery",   // jQuery rules
            "./.eslintrc-misc",     // Miscellaneous rules
        ),
        plugins: {
            "magento-coding-standard-eslint-plugin": magentoCodingStandardEslintPlugin,
        }
    },
    {
        ignores: ['**/eslint/rules/*.js'],
        languageOptions: {
            sourceType: "script"
        },
        rules: {
            strict: ["error", "function"]  // Enforce "use strict" in functions
        }
    }
]);
```

--------------------------------

### Preview PHPCBF Fixes with PHPCS

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Perform a dry run using PHPCS with the --report=diff option to preview the changes PHPCBF would make without actually modifying files.

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyVendor/MyExtension --report=diff
```

--------------------------------

### Run ESLint on JavaScript Files

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Executes ESLint to check JavaScript files against Magento coding standards. Specify the target directory for linting.

```bash
# Run ESLint on JavaScript files
npm run eslint -- app/code/MyVendor/MyModule/view/frontend/web/js
```

--------------------------------

### Run PHP_CodeSniffer with Custom Ruleset

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Execute PHP_CodeSniffer using a custom ruleset file to check code quality in a specified directory.

```bash
vendor/bin/phpcs --standard=./ruleset.xml app/code/MyVendor
```

--------------------------------

### Run Rector PHP for Specific Magento Project Path

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Process a specific Magento project path with Rector PHP, providing the project's autoload file.

```bash
vendor/bin/rector process MAGENTO_PATH --dry-run --autoload-file MAGENTO_AUTOLOAD_FILE
```

--------------------------------

### Run Rector for PHP Upgrades (Apply Changes)

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Applies PHP code upgrades using Rector for compatibility with PHP 8.0/8.1. Ensure to remove the --dry-run flag to modify files.

```bash
# Run Rector on Magento project code
vendor/bin/rector process magento2/app/code/MyVendor/MyModule \
    --dry-run \
    --autoload-file magento2/vendor/autoload.php

# Apply changes (remove --dry-run)
vendor/bin/rector process magento2/app/code/MyVendor/MyModule \
    --autoload-file magento2/vendor/autoload.php
```

--------------------------------

### Analyze Code with Magento2 Standard

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Run PHP_CodeSniffer to analyze your Magento 2 extension code using the Magento2 standard.

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyAwesomeExtension
```

--------------------------------

### Run Rector for PHP Upgrades (Dry Run)

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Performs a dry run of Rector to show potential PHP code changes for compatibility with PHP 8.0/8.1 without modifying files. Useful for reviewing changes before applying them.

```bash
# Dry run - show what would be changed without modifying files
vendor/bin/rector process Magento2 Magento2Framework PHP_CodeSniffer \
    --dry-run \
    --autoload-file vendor/squizlabs/php_codesniffer/autoload.php
```

--------------------------------

### Run Specific PHPUnit Test Class

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Execute a single PHPUnit test class to isolate and verify specific functionality.

```bash
vendor/bin/phpunit Magento2/Tests/Security/XssTemplateUnitTest.php
```

--------------------------------

### PHP Interface Naming Convention

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Ensures interfaces follow Magento's naming convention by including the 'Interface' suffix. Use this to maintain consistency in API definitions.

```php
<?php
// BAD: Interface without 'Interface' suffix
// Will trigger Magento2.NamingConvention.InterfaceName.WrongInterfaceName

namespace MyVendor\MyModule\Api;

interface ProductRepository  // Missing 'Interface' suffix
{
    public function get(int $id);
}

interface Searchable  // Missing 'Interface' suffix
{
    public function search(string $query): array;
}

// GOOD: Properly named interfaces
namespace MyVendor\MyModule\Api;

interface ProductRepositoryInterface
{
    /**
     * Get product by ID
     *
     * @param int $id
     * @return \MyVendor\MyModule\Api\Data\ProductInterface
     * @throws \Magento\Framework\Exception\NoSuchEntityException
     */
    public function get(int $id): ProductInterface;

    /**
     * Save product
     *
     * @param \MyVendor\MyModule\Api\Data\ProductInterface $product
     * @return \MyVendor\MyModule\Api\Data\ProductInterface
     */
    public function save(ProductInterface $product): ProductInterface;
}

interface SearchableInterface
{
    /**
     * @param string $query
     * @return array
     */
    public function search(string $query): array;
}
```

--------------------------------

### Detect Legacy Magento 1 Patterns

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Use this sniff to identify Magento 1.x patterns that are incompatible with Magento 2. It flags direct usage of Mage class methods and instantiation of legacy model/helper classes.

```php
<?php
// BAD: Magento 1.x patterns - will trigger Magento2.Legacy.MageEntity.FoundLegacyEntity

Mage::helper('catalog');
Mage::getModel('catalog/product');
Mage::getSingleton('core/session');
Mage::app()->getStore();
Mage::getStoreConfig('section/group/field');

$model = new Mage_Catalog_Model_Product();
$helper = new Mage_Core_Helper_Data();
$block = new Enterprise_Banner_Block_Widget_Banner();

// GOOD: Magento 2 patterns using dependency injection
use Magento\Catalog\Api\ProductRepositoryInterface;
use Magento\Catalog\Helper\Data as CatalogHelper;
use Magento\Customer\Model\Session;
use Magento\Framework\App\Config\ScopeConfigInterface;

class ProductService
{
    public function __construct(
        private ProductRepositoryInterface $productRepository,
        private CatalogHelper $catalogHelper,
        private Session $customerSession,
        private ScopeConfigInterface $scopeConfig
    ) {}

    public function getProduct(string $sku): \Magento\Catalog\Api\Data\ProductInterface
    {
        return $this->productRepository->get($sku);
    }

    public function getConfigValue(string $path): mixed
    {
        return $this->scopeConfig->getValue($path);
    }
}

```

--------------------------------

### Detect Discouraged PHP Functions

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Warns about native PHP functions that should be replaced with Magento framework equivalents for better security and consistency. For file operations, use \Magento\Framework\Filesystem\DriverInterface. For type checking, use language constructs.

```php
<?php
// BAD: Native PHP file functions - use Magento\Framework\Filesystem\DriverInterface

// File operations
fopen('file.txt', 'r');     // Use DriverInterface::fileOpen
fclose($handle);            // Use DriverInterface::fileClose
fwrite($handle, $data);     // Use DriverInterface::fileWrite
file_get_contents('file');  // Use DriverInterface::fileGetContents
file_put_contents('f', $d); // Use DriverInterface::filePutContents
file_exists('path');        // Use DriverInterface::isExists
mkdir('dir');               // Use DriverInterface::createDirectory
rmdir('dir');               // Use DriverInterface::deleteDirectory
copy('src', 'dest');        // Use DriverInterface::copy
rename('old', 'new');       // Use DriverInterface::rename
unlink('file');             // Use DriverInterface::deleteFile

// Type checking - use language constructs
is_null($var);              // Use === null comparison
intval($var);               // Use (int) cast
strval($var);               // Use (string) cast
sizeof($array);             // Use count()

```

```php
// GOOD: Using Magento framework classes
use Magento\Framework\Filesystem\DriverInterface;
use Magento\Framework\Filesystem\Io\File;

class FileProcessor
{
    public function __construct(
        private DriverInterface $driver,
        private File $fileIo
    ) {}

    public function readFile(string $path): string
    {
        if ($this->driver->isExists($path)) {
            return $this->driver->fileGetContents($path);
        }
        return '';
    }

    public function writeFile(string $path, string $content): void
    {
        $this->driver->filePutContents($path, $content);
    }

    public function getPathInfo(string $path): array
    {
        return $this->fileIo->getPathInfo($path);
    }
}

```

--------------------------------

### Analyze Magento 2 Code with PHPCS

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Execute PHP_CodeSniffer to analyze your Magento 2 code against the Magento2 standard. Specify the path to your extension and optionally file extensions.

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyVendor/MyExtension
```

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyVendor/MyExtension --extensions=php,phtml
```

--------------------------------

### Verify Sniffer Code with Magento Standard

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Check if the sniffer code itself adheres to the Magento Coding Standard.

```bash
vendor/bin/phpcs --standard=Magento2 Magento2/ --extensions=php
```

--------------------------------

### PHP Class and Interface PHPDoc Formatting

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Enforces proper PHPDoc formatting for classes and interfaces, including meaningful descriptions and correct usage of tags like @deprecated and @see. Avoids redundant or forbidden tags.

```php
<?php
// BAD: Meaningless or redundant PHPDoc comments
// Will trigger Magento2.Commenting.ClassAndInterfacePHPDocFormatting.InvalidDescription

/**
 * Product class
 */
class Product  // Description just repeats the class name
{
}

/**
 * @author John Doe
 * @package MyVendor\MyModule
 * @category Catalog
 */
class Category  // Forbidden tags: @author, @package, @category, @subpackage
{
}

/**
 * @deprecated
 */
class OldClass  // @deprecated without explanation
{
}

// GOOD: Meaningful PHPDoc with proper deprecation
/**
 * Handles product data transformation for API responses.
 * Converts internal product representation to the format required by external systems.
 */
class ProductDataTransformer
{
    // Implementation
}

/**
 * Provides catalog search functionality using Elasticsearch.
 *
 * @deprecated Search functionality moved to dedicated module.
 * @see \MyVendor\Search\Model\SearchEngine Use the new search engine implementation.
 */
class CatalogSearch
{
    // Legacy implementation
}

/**
 * Service contract for managing customer addresses.
 * Implements CRUD operations with validation and event dispatching.
 *
 * @api
 */
interface AddressManagementInterface
{
    // Interface methods
}
```

--------------------------------

### Set Magento Coding Standard Dependency

Source: https://github.com/magento/magento-coding-standard/wiki/Magento-Coding-Standard-Versioning

To ensure users always follow the latest version of the Coding Standard, set the dependency to "*". This applies to core developers, community contributors, system integrators, and extension developers.

```json
    "require-dev": {
        ...
        "magento/magento-coding-standard": "*",
        ...
    }
```

--------------------------------

### Use ViewModels Instead of Helpers in Magento Templates

Source: https://github.com/magento/magento-coding-standard/blob/develop/Magento2/Sniffs/Templates/ThisInTemplateSniff.md

Refactor helper calls in PHTML templates to use ViewModels. This promotes better separation of concerns and maintainability.

```php
<?php $viewModel = $block->getViewModel(); ?>
```

```php
<?php $viewModel = $block->getData('viewModel'); ?>
```

--------------------------------

### Generate Detailed PHPCS Report

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Generate a comprehensive report from PHP_CodeSniffer analysis, including full details of violations found.

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyVendor/MyExtension --report=full
```

--------------------------------

### Rector Rules for PHP Upgrades

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Demonstrates specific Rector rules applied within the Magento Coding Standard for PHP upgrades, such as fixing null parameters in string functions and removing redundant 'final' keywords from private methods.

```php
<?php
// Rector rules included in Magento Coding Standard:

// ReplaceMbStrposNullLimit - Fix null offset parameter
// Before:
mb_strpos("pattern", "subject", null, "encoding");
// After:
mb_strpos("pattern", "subject", 0, "encoding");

// ReplaceNewDateTimeNull - Fix null DateTime constructor
// Before:
new DateTime(null);
// After:
new DateTime();

// ReplacePregSplitNullLimit - Fix null limit parameter
// Before:
preg_split('/\s/', $string, null);
// After:
preg_split('/\s/', $string, -1);

// FinalPrivateToPrivateVisibilityRector - Remove final from private methods
// Before:
final private function myMethod() {}
// After:
private function myMethod() {}
```

--------------------------------

### Configure PHPCS to use Magento2 Standard

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Configure PHP_CodeSniffer to recognize the Magento2 standard by adding the installed_paths to your composer.json file. This ensures PHPCS can find and use the Magento rules.

```json
"post-install-cmd": [
  "([ $COMPOSER_DEV_MODE -eq 0 ] || vendor/bin/phpcs --config-set installed_paths ../../magento/magento-coding-standard/)"
]
```

--------------------------------

### Detect Insecure PHP Functions

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Identifies dangerous PHP functions that can lead to security vulnerabilities. Use Magento's secure alternatives like \Magento\Framework\Shell::execute and \Magento\Framework\Serialize\SerializerInterface.

```php
<?php
// BAD: These functions trigger Magento2.Security.InsecureFunction errors

// Command execution - use \Magento\Framework\Shell::execute instead
exec('ls -la');
shell_exec('cat /etc/passwd');
system('whoami');
passthru('dir');
proc_open('cmd', $descriptorspec, $pipes);

// Serialization - use \Magento\Framework\Serialize\SerializerInterface instead
$data = serialize($object);  // Use SerializerInterface::serialize
$obj = unserialize($string); // Use SerializerInterface::unserialize

// Weak hashing
$hash = md5($password); // Use improved hash functions (SHA-256, SHA-512)

// Random number generation
$rand = mt_rand(1, 100); // Use random_int() instead

```

```php
// GOOD: Using Magento's secure alternatives
use Magento\Framework\Serialize\SerializerInterface;
use Magento\Framework\Shell;

class MyClass
{
    public function __construct(
        private SerializerInterface $serializer,
        private Shell $shell
    ) {}

    public function processData(array $data): string
    {
        return $this->serializer->serialize($data);
    }

    public function executeCommand(string $command): string
    {
        return $this->shell->execute($command);
    }
}

```

--------------------------------

### Detect Raw SQL Queries

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Identifies raw SQL statements to prevent SQL injection vulnerabilities. Use Magento's database abstraction layer (ResourceConnection and Select) for safe database interactions.

```php
<?php
// BAD: Raw SQL queries - will trigger Magento2.SQL.RawQuery.FoundRawSql

$sql = "SELECT * FROM users WHERE id = " . $userId;
$sql = 'UPDATE products SET price = 100 WHERE sku = "ABC"';
$sql = "DELETE FROM logs WHERE date < '2023-01-01'";
$query = "INSERT INTO table_name VALUES (1, 2, 3)";

$connection->query("SELECT * FROM customers");
$connection->query('DROP TABLE sensitive_data');

// Heredoc/Nowdoc also detected
$sql = <<<SQL
SELECT * FROM orders
WHERE customer_id = {$customerId}
SQL;

```

```php
// GOOD: Use Magento's database abstraction layer
use Magento\Framework\App\ResourceConnection;
use Magento\Framework\DB\Select;

class OrderRepository
{
    public function __construct(
        private ResourceConnection $resourceConnection
    ) {}

    public function getOrdersByCustomer(int $customerId): array
    {
        $connection = $this->resourceConnection->getConnection();
        $tableName = $this->resourceConnection->getTableName('sales_order');

        $select = $connection->select()
            ->from($tableName)
            ->where('customer_id = ?', $customerId)
            ->order('created_at DESC');

        return $connection->fetchAll($select);
    }

    public function updateOrderStatus(int $orderId, string $status): void
    {
        $connection = $this->resourceConnection->getConnection();
        $tableName = $this->resourceConnection->getTableName('sales_order');

        $connection->update(
            $tableName,
            ['status' => $status],
            ['entity_id = ?' => $orderId]
        );
    }
}

```

--------------------------------

### Optimized Array Merging After Loop

Source: https://github.com/magento/magento-coding-standard/blob/develop/Magento2/Sniffs/Performance/ForeachArrayMergeSniff.md

To improve performance, collect all arrays within the loop and then merge them once after the loop completes. This approach significantly reduces the overhead associated with repeated merging.

```php
$options = [];
foreach ($configurationSources as $source) {
    // code here
    $options[] = $source->getOptions();
}

$options = array_merge([], ...$options);
```

--------------------------------

### Dry Run Rector PHP for Magento Coding Standard

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Execute Rector PHP with the Magento Coding Standard rules in dry-run mode to see potential changes without applying them.

```bash
vendor/bin/rector process Magento2 Magento2Framework PHP_CodeSniffer --dry-run --autoload-file vendor/squizlabs/php_codesniffer/autoload.php
```

--------------------------------

### Filter PHPCS Analysis Results

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Run PHP_CodeSniffer to show only errors (severity 10) and suppress warnings (severity 0) for a focused analysis.

```bash
vendor/bin/phpcs --standard=Magento2 app/code/MyVendor/MyExtension --error-severity=10 --warning-severity=0
```

--------------------------------

### Fix Code Issues Automatically with phpcbf

Source: https://github.com/magento/magento-coding-standard/blob/develop/README.md

Use the phpcbf tool to automatically fix code style violations identified by the Magento2 standard.

```bash
vendor/bin/phpcbf --standard=Magento2 app/code/MyAwesomeExtension
```

--------------------------------

### Avoid array_merge in Loops for Performance

Source: https://context7.com/magento/magento-coding-standard/llms.txt

This sniff detects the inefficient use of array_merge() inside loops, which can lead to performance issues. Prefer using the spread operator, direct array assignment, or array_reduce for better performance.

```php
<?php
// BAD: array_merge in loop - will trigger Magento2.Performance.ForeachArrayMerge
$result = [];
foreach ($items as $item) {
    $result = array_merge($result, $item->getData());
}

for ($i = 0; $i < count($products); $i++) {
    $allAttributes = array_merge($allAttributes, $products[$i]->getAttributes());
}

// GOOD: Use spread operator or array assignment
$result = [];
foreach ($items as $item) {
    $result[] = $item->getData(); // If you want nested arrays
}
$flattened = array_merge(...$result); // Merge once at the end

// GOOD: Direct array assignment
$result = [];
foreach ($items as $item) {
    foreach ($item->getData() as $key => $value) {
        $result[$key] = $value;
    }
}

// GOOD: Use array_reduce for complex merging
$result = array_reduce($items, function ($carry, $item) {
    return array_merge($carry, $item->getData());
}, []);

// GOOD: Pre-allocate and assign
$result = [];
foreach ($items as $item) {
    $data = $item->getData();
    foreach ($data as $key => $value) {
        $result[$key] = $value;
    }
}

```

--------------------------------

### Auto-fix Violations with PHPCBF

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Use PHP Code Beautifier and Fixer (PHPCBF) to automatically correct fixable coding standard violations within your Magento 2 extension.

```bash
vendor/bin/phpcbf --standard=Magento2 app/code/MyVendor/MyExtension
```

--------------------------------

### Inefficient Array Merging in Loop

Source: https://github.com/magento/magento-coding-standard/blob/develop/Magento2/Sniffs/Performance/ForeachArrayMergeSniff.md

Avoid using `array_merge` inside a loop as it is a resource-intensive operation that can slow down execution and increase CPU usage. This pattern is common but should be refactored for better performance.

```php
$options = [];
foreach ($configurationSources as $source) {
    // code here
    $options = array_merge($options, $source->getOptions());
}
```

--------------------------------

### Fix Specific Sniffs with PHPCBF

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Apply PHPCBF to fix only violations related to specific sniffs, such as Magento2.Templates.ThisInTemplate, for targeted code correction.

```bash
vendor/bin/phpcbf --standard=Magento2 app/code/MyVendor/MyExtension --sniffs=Magento2.Templates.ThisInTemplate
```

--------------------------------

### Custom PHP_CodeSniffer Ruleset

Source: https://context7.com/magento/magento-coding-standard/llms.txt

Defines a custom ruleset for PHP_CodeSniffer, extending Magento2 standards and configuring specific rules and exclusions.

```xml
<?xml version="1.0"?>
<ruleset name="MyProjectStandard">
    <description>Custom coding standard based on Magento2</description>

    <!-- Include Magento2 standard as base -->
    <rule ref="Magento2"/>

    <!-- Exclude specific sniffs -->
    <rule ref="Magento2.Functions.StaticFunction">
        <exclude-pattern>*/Setup/*</exclude-pattern>
        <exclude-pattern>*/Test/*</exclude-pattern>
    </rule>

    <!-- Adjust severity levels -->
    <rule ref="Magento2.Performance.ForeachArrayMerge">
        <severity>9</severity>
        <type>error</type>
    </rule>

    <!-- Configure line length -->
    <rule ref="Generic.Files.LineLength">
        <properties>
            <property name="lineLimit" value="140"/>
            <property name="absoluteLineLimit" value="0"/>
        </properties>
    </rule>

    <!-- Exclude vendor and generated directories -->
    <exclude-pattern>*/vendor/*</exclude-pattern>
    <exclude-pattern>*/generated/*</exclude-pattern>
    <exclude-pattern>*
.min
.js$</exclude-pattern>

    <!-- Only check specific file types -->
    <arg name="extensions" value="php,phtml"/>
</ruleset>
```

--------------------------------

### Update composer.json for Magento Coding Standard

Source: https://github.com/magento/magento-coding-standard/wiki/Release

Modify the composer.json file to include the Magento Coding Standard as a development dependency. This is typically done when testing local changes or preparing for a release.

```json
{
    ...
    "require-dev": {
        ...
        "magento/magento-coding-standard": "dev-[branch]"
        ...
    }
    ...
    "minimum-stability": "dev",
    "repositories": [
        {
            "type": "git",
            "url": "https://github.com/[fork]/magento-coding-standard"
        }

    ]

}
```

--------------------------------

### Replace $this with $block in PHTML Templates

Source: https://context7.com/magento/magento-coding-standard/llms.txt

This sniff enforces the use of $block instead of the deprecated $this in PHTML templates. It can be auto-fixed by phpcbf. Avoid using $this->helper() directly; prefer ViewModels.

```php
<?php
// BAD: Using $this in templates - will trigger Magento2.Templates.ThisInTemplate.FoundThis
// This is deprecated and will be auto-fixed by phpcbf
?>
<div class="product-info">
    <h1><?= $this->escapeHtml($this->getProduct()->getName()) ?></h1>
    <p><?= $this->escapeHtml($this->getProduct()->getDescription()) ?></p>
    <?= $this->getChildHtml('product.info.price') ?>
</div>

<?php
// BAD: Using helpers in templates - will trigger Magento2.Templates.ThisInTemplate.FoundHelper
$helper = $this->helper('Magento\Catalog\Helper\Data');
?>

<?php
// GOOD: Using $block (auto-fixable from $this)
?>
<div class="product-info">
    <h1><?= $block->escapeHtml($block->getProduct()->getName()) ?></h1>
    <p><?= $block->escapeHtml($block->getProduct()->getDescription()) ?></p>
    <?= $block->getChildHtml('product.info.price') ?>
</div>

<?php
// GOOD: Using ViewModel instead of helpers
/** @var \MyVendor\MyModule\ViewModel\ProductViewModel $viewModel */
$viewModel = $block->getViewModel();
?>
<div class="product-data">
    <span><?= $block->escapeHtml($viewModel->getFormattedPrice()) ?></span>
</div>

```

--------------------------------

### Avoid $this in Magento Templates

Source: https://github.com/magento/magento-coding-standard/blob/develop/Magento2/Sniffs/Templates/ThisInTemplateSniff.md

In PHTML templates, use `$block` instead of `$this` to access the current block. This is a deprecated practice that may be removed in future versions.

```php
<?php $_incl = $this->helper(<helper_class>)->...; ?>
```

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