Dependency Injection Laravel Package

Getting Started

Minimal Steps

1. Installation:

   composer require draw/dependency-injection
   

   Add the package to your composer.json dependencies.

2. First Use Case:

   • Use the IntegrationTrait in your bundle’s DependencyInjection extension to integrate subcomponents.
   • Example: Extend a base bundle (e.g., DrawFrameworkExtraBundle) by integrating smaller components (e.g., MyComponent, MyOtherComponent).

3. Key Files to Review:

   • IntegrationTrait (for bundle integration logic).
   • ExtendableExtensionTrait (for extending Symfony’s ContainerBuilder).
   • Component-specific integration classes (e.g., MyComponentIntegration).

Implementation Patterns

Core Workflow

1. Define Component Integrations:

   • In your main bundle’s DependencyInjection extension, list subcomponent integrations in provideExtensionClasses().
   • Example:

     protected function provideExtensionClasses(): array {
         return [
             MyComponentIntegration::class,
             MyOtherComponentIntegration::class,
         ];
     }
     

2. Automatic Registration:

   • Call registerDefaultIntegrations() in the bundle’s constructor to auto-load integrations.
   • The trait handles instantiation and validation of integration classes.

3. Configuration Handling:

   • Use loadIntegrations() to process subcomponent configs only if enabled: true.
   • Example YAML:

     example_my_bundle:
         my_component:
             enabled: true
             # Component-specific config
     

4. Service Prepending:

   • Use prependIntegrations() to modify the container before your bundle’s services are loaded.
   • Example:

     public function prepend(ContainerBuilder $container): void {
         $this->prependIntegrations($container, 'example_my_bundle');
     }
     

Integration Tips

• Modular Bundles: Ideal for splitting large bundles into smaller, reusable components (e.g., AuthBundle, CacheBundle).
• Conditional Loading: Disable components via YAML (enabled: false) to avoid conflicts or reduce overhead.
• Configuration Inheritance: Subcomponents can extend the main bundle’s configuration by overriding getConfiguration().

Gotchas and Tips

Pitfalls

1. Circular Dependencies:

   • If subcomponents depend on each other, ensure prependIntegrations() order matches dependency resolution.
   • Fix: Explicitly order integrations in provideExtensionClasses().

2. Missing Integration Classes:

   • The trait silently skips non-existent classes. Verify with:

     if (!class_exists(MyComponentIntegration::class)) {
         throw new \RuntimeException('Integration class missing!');
     }
     

3. Configuration Overrides:

   • Subcomponent configs merge with the main bundle’s config. Use parent::load() carefully to avoid overwrites.

4. Namespace Collisions:

   • Ensure subcomponent integration classes have unique namespaces (e.g., Example\Component\Auth\DependencyInjection\AuthIntegration).

Debugging

• Check Loaded Integrations:

  var_dump($this->integrations); // Inspect registered integrations in `load()`.
  

• Enable Debug Mode: Symfony’s ContainerBuilder logs service modifications. Use:

  $container->setDebug(true);
  

Extension Points

1. Custom Integration Logic:

   • Override loadIntegrations() to add pre/post-processing (e.g., validation).

   protected function loadIntegrations(array $configs, ContainerBuilder $container): array {
       $config = parent::loadIntegrations($configs, $container);
       // Custom logic here
       return $config;
   }
   

2. Dynamic Component Discovery:

   • Use Composer\Autoload\ClassLoader to auto-discover integrations in provideExtensionClasses():

   $loader = new \Composer\Autoload\ClassLoader();
   $loader->addPsr4('Example\Component\\', __DIR__.'/../../../vendor');
   $integrationClasses = $loader->findFiles('*Integration');
   

3. Environment-Specific Configs:

   • Load integrations conditionally based on environment variables:

   if ($_ENV['APP_ENV'] === 'prod') {
       $this->integrations[] = new ProdOptimizationIntegration();
   }