从Symfony 3.4迁移至Symfony 4：自定义Bundle适配指导请求

Hey there! I’ve tackled this exact problem with several legacy Symfony 3.4 projects that had tons of custom Bundles, so let’s break down how to adapt them to Symfony 4’s structure without pulling your hair out.

First off, Symfony 4 (and later) uses Flex to streamline the directory structure—no more mandatory Bundle wrappers. Instead, code lives directly under src/, organized by responsibility: Controller/, Entity/, Service/, etc. The good news? You don’t have to migrate all your Bundles at once; take it one at a time to avoid chaos.

Pick a small, low-risk Bundle to start with (like a utility or logging Bundle) to work out the kinks before moving to larger ones.

Substep 2.1: Relocate Files to the Root src/ Directory #

For each component in your Bundle:

• Controllers: Move src/YourBundle/Controller/YourController.php to src/Controller/YourController.php, then update the namespace from Your\YourBundle\Controller to App\Controller.
• Entities/Repositories: Shift them to src/Entity/ and update namespaces to App\Entity.
• Services: Move to src/Service/ with the App\Service namespace.
• Templates: Bundle templates (e.g., src/YourBundle/Resources/views/) can go to templates/your_bundle/ (keeping them grouped by old Bundle name helps with the transition) or directly into templates/ if they fit a broader category.
• Commands: Relocate to src/Command/ with the App\Command namespace—Symfony will auto-register these.

Substep 2.2: Update All Configuration References #

You’ll need to fix every place where your Bundle was referenced:

• Routes: Replace @YourBundle/Resources/config/routing.yml in your route config with the new path (e.g., config/routes/your_bundle.yaml) or merge the routes directly into config/routes.yaml.
• Services: In services.yaml, update class references from Your\YourBundle\Service\YourService to App\Service\YourService. Symfony 4 auto-registers most services in src/, so you can likely remove old Bundle-specific service definitions unless they have special configuration.
• Template Calls: Change Twig includes like {{ include('@YourBundle/Default/index.html.twig') }} to {{ include('your_bundle/Default/index.html.twig') }} (matching your new template directory structure).

If your Bundle had a custom extension class (e.g., YourBundleExtension.php) for configuration, you have two options:

1. Temporary Keep: Leave the extension in place (move it to src/DependencyInjection/) until you refactor the config into Flex-style packages under config/packages/.
2. Refactor: Move the configuration logic to a new file like config/packages/your_bundle.yaml and define parameters/services directly there.

Once you’ve moved all files and updated references, delete the main Bundle class (e.g., YourBundle.php) and remove its entry from config/bundles.php. At this point, that old Bundle no longer exists—its code is now part of the core App namespace.

After each migration step (e.g., moving controllers, updating services), run your application and tests to catch issues early:

• Use php bin/console debug:container to verify services are registered correctly.
• Check routes with php bin/console debug:router.
• Load pages that use the migrated code to ensure templates and logic work as expected.

• For shared code across multiple old Bundles, create a src/Shared/ directory to keep that logic organized instead of scattering it across src/.
• If you have Bundle-specific assets (CSS/JS), move them to public/assets/your_bundle/ and update asset references in templates.
• Use Symfony’s deprecation logs to catch any leftover references to the old Bundle—run php bin/console debug:deprecations to see what’s still hanging around.

内容的提问来源于stack exchange，提问作者Jigar Pancholi