Key Core Changes from Drupal 9 to Drupal 10

Here’s a comprehensive list of key differences between Drupal 10 and Drupal 9, focusing on technical updates, feature enhancements, and removed/added dependencies:

1. Dependency Updates

• Symfony 6: Upgraded from Symfony 4, providing better performance and modern PHP features.
• CKEditor 5: Replaces CKEditor 4 as the default WYSIWYG editor with improved features.
• PHP Requirements:
  • Minimum PHP version: 8.1.
  • Deprecated PHP features are no longer supported.

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2. Removed Deprecated Code

• All APIs, functions, and classes marked as deprecated in Drupal 9 are removed in Drupal 10.
• Modules and themes must update to use non-deprecated alternatives. See reference below.

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3. Frontend Updates

• Olivero: New default frontend theme, replacing Bartik.
• Claro: New default admin theme, replacing Seven.
• Starterkit Theme Generator:
  • Provides a tool to create custom themes based on Starterkit templates.
  • Replaces Classy as the base theme.

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4. New Features and APIs

• Typed Data System Enhancements:
  • Improved validation and better integration with external data sources.
• Twig 3 Support:
  • Modernized templating features for better performance.
• Improved Layout Builder:
  • Enhanced drag-and-drop functionality.
  • Better block management and support for CSS Grid.
• Automatic Updates Initiative:
  • Early support for automatic updates.
• Project Browser Initiative:
  • Allows users to discover and install contributed modules/themes directly from the admin UI.

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5. JavaScript Modernization

• jQuery UI Removed:
  • Modern JavaScript replaces deprecated jQuery UI components.
• Core JavaScript now aligns with ES6+ standards.

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6. Multilingual Enhancements

• Simplified configuration workflows for multilingual setups.
• Improved language management UI.

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7. New Patterns in Drupal 10

To ensure compatibility with Drupal 10, rely on modern design patterns:

1. Dependency Injection:

   • Instead of relying on procedural functions (e.g., \Drupal::service()), inject services via constructors.
   • Example:

     public function __construct(ConfigFactoryInterface $config_factory) {
       $this->configFactory = $config_factory;
     }

2. Entity Type Manager:

   • Use \Drupal::entityTypeManager() for loading, creating, and saving entities.

3. Service-Based Caching:

   • Use cache tags and contexts via the CacheBackendInterface service.

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Summary of Removed Features

Removed Feature	Replacement/Alternative
CKEditor 4	CKEditor 5
Deprecated Modules	Updated workflows (e.g., Config Translation folded in).
jQuery UI	Replaced with modern JavaScript solutions.
SimpleTest	Replaced by PHPUnit for testing.
Bartik & Seven themes	Olivero & Claro themes.

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Deprecations

Below are common deprecated functions and classes removed in Drupal 10: Here is a comprehensive list of deprecated functions and classes that have been removed or replaced in Drupal 10, along with their replacements or alternatives.

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Deprecated Functions

Deprecated Function	Replacement/Alternative
drupal_set_message()	Use \Drupal::messenger()->addMessage()
drupal_get_path()	Use \Drupal::service('extension.path.resolver')->getPath()
drupal_static()	Use dependency injection to manage services or static caching.
entity_load()	Use \Drupal::entityTypeManager()->getStorage($entity_type)->load($id)
entity_create()	Use \Drupal::entityTypeManager()->getStorage($entity_type)->create($values)
file_create_url()	Use file_url_transform_relative(file_url_generator()->generate($uri))
db_query()	Use the \Drupal::database() service with prepared statements or parameterized queries.
menu_tree_output()	Use the MenuTreeBuilder class instead.
path_to_theme()	Use \Drupal::theme()->getActiveTheme()->getPath()
user_access()	Use \Drupal::currentUser()->hasPermission($permission)
url()	Use \Drupal\Core\Url::fromRoute() or Url::fromUri() for link generation.
check_plain()	Use Html::escape() from Drupal\Component\Utility\Html.
format_date()	Use \Drupal::service('date.formatter')->format()

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Deprecated Classes

Deprecated Class	Replacement/Alternative
File	Use \Drupal\file\Entity\File.
Config	Use the ConfigFactoryInterface service via dependency injection.
EntityStorageControllerInterface	Use EntityStorageInterface.
Cache	Use the CacheBackendInterface service for caching functionality.
Path	Use \Drupal\Core\Path\PathMatcher or \Drupal\Core\Path\PathProcessor services.
Drupal\Component\Utility\String	Use \Drupal\Component\Utility\Html, SafeMarkup, or Xss depending on the use case.
EntityManager	Use EntityTypeManager.
TypedDataManager	Use TypedDataManagerInterface.

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Deprecated Constants

Deprecated Constant	Replacement/Alternative
REQUEST_TIME	Use $request->getRequestTime() from the Request object.
DRUPAL_BOOTSTRAP_CONFIGURATION	Use specific services to bootstrap configuration.
DRUPAL_ROOT	Use \Drupal::root() for the Drupal root directory path.

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Removed Modules

Certain core modules were deprecated in Drupal 9 and are removed in Drupal 10. If you use them, you must replace them with alternatives:

Removed Module	Alternative/Action Required
Quick Edit	No direct replacement. Use admin views or edit forms instead.
Aggregator	Use external RSS aggregators or contributed modules.
SimpleTest	Use PHPUnit for automated testing.
Forum	Use contributed modules such as Advanced Forum.
HAL (REST Module)	Use JSON:API for modern and efficient RESTful APIs.
RDF	Evaluate if RDF support is still required; use third-party modules if needed.

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Key Resources

1. Drupal 10 Change Records
2. Upgrade Status Module
3. CKEditor 5 in Drupal 10