Altering Existing Services, Providing Dynamic Services

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Alter existing service using ServiceProviderBase and Custom compiler pass.

REF: Altering existing services, providing dynamic services

修改存在的Service

  • ServiceProvider
    在模块根目录下创建ModuleNameServiceProvider class实现\Drupal\Core\DependencyInjection\ServiceModifierInterface或继承ServiceProviderBase

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    // 必须
    namespace Drupal\my_module;

    use Drupal\Core\DependencyInjection\ContainerBuilder;
    use Drupal\Core\DependencyInjection\ServiceProviderBase;

    // @note: You only need Reference, if you want to change service arguments.
    use Symfony\Component\DependencyInjection\Reference;

    /**
     * Modifies the language manager service.
     */
    // 名字格式必须，继承类必须，方法必须
    class MyModuleServiceProvider extends ServiceProviderBase {

      /**
       * {@inheritdoc}
       */
      public function alter(ContainerBuilder $container) {
        // Overrides language_manager class to test domain language negotiation.
        // Adds entity_type.manager service as an additional argument.
        $definition = $container->getDefinition('language_manager');
        $definition->setClass('Drupal\language_test\LanguageTestManager')
          ->addArgument(new Reference('entity_type.manager'));
      }
    }

  • 覆盖已存在的service

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    language_manager:
      class: Drupal\module_name\Service\MyLanguageManager
      arguments: ['@language.default']

  • 最后可以通过定义register()方法来动态的注册service，但是很少见

Custom compiler pass

Compiler pass是Container的扩展点，你可以用它覆写已存在service中的方法或添加新的方法。你也可以自己创建一个新的tag点供其他模块使用（如event_subscriber）

During the compilation, declaration files are parsed, parameters and configuration are resolved, “alias” are created and tagged services are processed.

在清缓存的过程中，Container会被编译，在编译过程中，所有container管理的service都会被注册到container中。在编译完成后，container会被缓存。
大多数情况下我们都不需要创建compiler pass，但是过程需要了解一下

Drupal如何编译container
  • index.php
    • …
    • $response = $kernel->handle($request);
      • …
      • $this->boot();
        • …
        • $this->initializeContainer(); 初始化容器
          • …
          • $container = $this->compileContainer();
            • $this->initializeServiceProviders();
              • $this->discoverServiceProviders(); 将*.service.yml文件和*ServiceProvider class分别存储到serviceYamls和serviceProviderClasses中
              • … 将实例化的*ServiceProvider类放入serviceProvider中
            • … 注册services到container
            • $container->compile();
    • …
创建compiler pass
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\compiler_module
	src\CompilerModuleServiceProvider
	src\Compiler\CompilerModuleExtensionPass

// CompilerModuleServiceProvider
namespace Drupal\compiler_module;

use Drupal\Core\DependencyInjection\ContainerBuilder;
use Drupal\Core\DependencyInjection\ServiceProviderBase;
use Drupal\compiler_module\Compiler\CompilerModuleExtensionPass;

class CompilerModuleServiceProvider extends ServiceProviderBase {

  /**
   * {@inheritdoc}
   */
   public function register(ContainerBuilder $container) {
      $container->addCompilerPass(new MyCustomExtensionPass());
   }
}


// CompilerModuleExtensionPass
namespace Drupal\compiler_module\Compiler;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;

class CompilerModuleExtensionPass implements CompilerPassInterface {

    /**
    * {@inheritdoc}
    */
    public function process(ContainerBuilder $container) {
        ... your work
    }

}