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beginner Phase 75 · Debugging Basics

Developer Mode

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Enabling Developer Mode

Switch to Developer Mode

# Enable developer mode
bin/magento deploy:mode:set developer

# Verify current mode
bin/magento deploy:mode:show

# Switch to production mode
bin/magento deploy:mode:set production

Mode Differences

// Developer Mode:
// - Auto-compilation disabled
// - Error display enabled
// - Static files not cached
// - Detailed error messages
// - File watching enabled

// Production Mode:
// - Auto-compilation enabled
// - Error display disabled
// - Static files cached
// - Minimal error messages
// - Performance optimized

Environment Configuration

// app/etc/env.php
return [
    'MAGE_MODE' => 'developer', // or 'production'
    
    'system' => [
        'default' => [
            'dev' => [
                'debug' => [
                    'debug_logging' => 1,
                    'profiler' => 0,
                ],
                'template' => [
                    'allow_symlink' => 1,
                ],
            ],
        ],
    ],
];

Key Points

  • Developer mode enables detailed error display
  • Never use developer mode in production
  • Static content deployment differs by mode
  • Developer mode has performance overhead

Static Content Deployment

Deploy Static Files

# Deploy all static content
bin/magento setup:static-content:deploy

# Deploy for specific theme
bin/magento setup:static-content:deploy -f Magento/luma

# Deploy for specific locale
bin/magento setup:static-content:deploy en_US

# Deploy with jobs (faster)
bin/magento setup:static-content:deploy -j 4

# Quick deploy (developer mode)
bin/magento setup:static-content:deploy --no-parent -t Magento/luma

Static Content Configuration

// app/etc/env.php
return [
    'static' => [
        'version' => '1.0.0',
    ],
    
    'deploy' => [
        'hoist' => 1,
    ],
];

File Symlinks

# Enable symlinks for development
bin/magento config:set dev/template/allow_symlink 1

# Check symlink status
bin/magento config:show dev/template/allow_symlink

Key Points

  • Deploy after theme or LESS/CSS changes
  • Use jobs flag for faster deployment
  • Symlinks speed up development
  • Cache static files in production

Error Display Settings

PHP Error Configuration

; php.ini settings for development
display_errors = On
error_reporting = E_ALL
log_errors = On
error_log = /var/log/php_errors.log

; Production settings
display_errors = Off
error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT
log_errors = On

Magento Error Handler

// app/bootstrap.php
\Magento\Framework\App\Bootstrap::run($initParams);

// Custom error handler
set_error_handler(function($errno, $errstr, $errfile, $errline) {
    $logger = \Magento\Framework\App\Bootstrap::getObjectManager()
        ->get(\Psr\Log\LoggerInterface::class);
    
    $logger->error($errstr, [
        'file' => $errfile,
        'line' => $errline,
    ]);
    
    return true;
});

Custom Error Page

// app/code/Vendor/Module/view/frontend/templates/error/404.phtml
<div class="page-not-found">
    <h1>404</h1>
    <p>Page not found.</p>
    <a href="<?= $block->getBaseUrl() ?>">Return to Home</a>
</div>

Key Points

  • Developer mode shows detailed errors
  • Production mode hides errors from users
  • Always log errors even when hidden
  • Custom error pages improve UX

Practice Problems

0 / 1 solved
Mode Configuration

Configure a Magento store for development with proper error display and static content settings.

Solution 
# 1. Set developer mode
bin/magento deploy:mode:set developer

# 2. Verify mode
bin/magento deploy:mode:show

# 3. Enable symlinks
bin/magento config:set dev/template/allow_symlink 1

# 4. Deploy static content
bin/magento setup:static-content:deploy -f

# 5. Clean cache
bin/magento cache:clean

Quiz

1. What does developer mode enable?

Question 1 options

2. How do you deploy static content?

Question 2 options

3. When should you use production mode?

Question 3 options

4. What is the benefit of symlinks in development?

Question 4 options

Flashcards

Question

Developer mode command?

Click to reveal answer

Answer

bin/magento deploy:mode:set developer

Question

Static content deploy?

Click to reveal answer

Answer

bin/magento setup:static-content:deploy

Question

Developer mode benefit?

Click to reveal answer

Answer

Detailed error display for debugging

Question

Production mode feature?

Click to reveal answer

Answer

Cached static files, hidden errors

Revision Notes

Key Takeaways

  • 1. Developer mode shows detailed errors and disables caching
  • 2. Use bin/magento deploy:mode:set to switch modes
  • 3. Deploy static content after theme changes
  • 4. Never use developer mode in production

Interview Tips

  • • Explain differences between developer and production mode
  • • Discuss when to deploy static content
  • • Know error display configuration

Cheat Sheet

Developer Mode

  • Set: bin/magento deploy:mode:set developer
  • Deploy: bin/magento setup:static-content:deploy
  • Errors: displayed in developer mode
  • Symlinks: enabled for faster dev