class BackendCompilerPass

Defines a compiler pass to allow automatic override per backend.

A module developer has to tag a backend service with "backend_overridable":


custom_service:
  class: ...
  tags:
    - { name: backend_overridable }

As a site admin you set the 'default_backend' in your services.yml file:

parameters:
default_backend:
sqlite;

As a developer for alternative storage engines you register a service with $your_backend.$original_service:


sqlite.custom_service:
  class: ...

Hierarchy

  • class \Drupal\Core\DependencyInjection\Compiler\BackendCompilerPass implements \Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface

Expanded class hierarchy of BackendCompilerPass

2 files declare their use of BackendCompilerPass
BackendCompilerPassTest.php in core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/BackendCompilerPassTest.php
CoreServiceProvider.php in core/lib/Drupal/Core/CoreServiceProvider.php

File

View on git.drupalcode.org

core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php, line 34

Namespace

Drupal\Core\DependencyInjection\Compiler
View source 
class BackendCompilerPass implements CompilerPassInterface {
  
  /**
   * {@inheritdoc}
   *
   * phpcs:ignore Drupal.Commenting.FunctionComment.VoidReturn
   * @return void
   */
  public function process(ContainerBuilder $container) {
    $driver_backend = NULL;
    if ($container->hasParameter('default_backend')) {
      $default_backend = $container->getParameter('default_backend');
      // Opt out from the default backend.
      if (!$default_backend) {
        return;
      }
    }
    else {
      try {
        $driver_backend = $container->get('database')
          ->driver();
        $default_backend = $container->get('database')
          ->databaseType();
        $container->set('database', NULL);
      } catch (\Exception $e) {
        // If Drupal is not installed or a test doesn't define database there
        // is nothing to override.
        return;
      }
    }
    foreach ($container->findTaggedServiceIds('backend_overridable') as $id => $attributes) {
      // If the service is already an alias it is not the original backend, so
      // we don't want to fallback to other storages any longer.
      if ($container->hasAlias($id)) {
        continue;
      }
      if ($container->hasDefinition("{$driver_backend}.{$id}") || $container->hasAlias("{$driver_backend}.{$id}")) {
        $container->setAlias($id, new Alias("{$driver_backend}.{$id}"));
      }
      elseif ($container->hasDefinition("{$default_backend}.{$id}") || $container->hasAlias("{$default_backend}.{$id}")) {
        $container->setAlias($id, new Alias("{$default_backend}.{$id}"));
      }
    }
  }

}

Members

Title Modifiers Object type Summary
BackendCompilerPass::process public function phpcs:ignore Drupal.Commenting.FunctionComment.VoidReturn

Buggy or inaccurate documentation? Please file an issue. Need support? Need help programming? Connect with the Drupal community.