Controller Callback Bundle Laravel Package

Product Decisions This Supports

• Middleware/Interceptors for Legacy Systems: Enables adding pre/post logic to controllers without modifying existing code, aligning with clean architecture principles.
• A/B Testing or Feature Flags: Quickly route traffic to alternate controller logic (e.g., preCallback for feature flag checks).
• Analytics/Logging: Inject instrumentation (e.g., timing, user tracking) without bloating controllers.
• Deprecation Paths: Gradually phase out old controllers by wrapping them in postCallback logic (e.g., logging deprecation warnings).
• Build vs. Buy: Justifies buying this over custom middleware if:
  • Team lacks Symfony expertise.
  • Need a lightweight, configurable solution (vs. building from scratch).
  • Symfony 2 is a legacy constraint (though Symfony 6+ has native alternatives like EventDispatcher).
• Roadmap for Migration: Use as a stopgap during Symfony 2 → 3/4/5 upgrades, replacing callbacks with modern middleware later.

When to Consider This Package

• Avoid if:
  • Using Symfony 3+: Native EventDispatcher or middleware is more maintainable.
  • Need complex logic: Callbacks are limited to simple function calls (no dependency injection or async tasks).
  • Performance-critical: Adds minimal overhead but isn’t optimized for high-throughput routes.
  • Modern stack: Prefer Laravel’s middleware or PHP 8 attributes (#[BeforeRoute]).
• Look elsewhere for:
  • Symfony 2 alternatives: nelmio/cors-bundle (for CORS), or custom middleware.
  • Laravel: Use middleware or route filters.
  • Microservices: Offload pre/post logic to API gateways or sidecars.

How to Pitch It (Stakeholders)

To Executives: "This bundle lets us add lightweight ‘before/after’ logic to existing Symfony 2 controllers without rewriting them—think of it as ‘sticky notes’ for your routes. Use cases include A/B testing, analytics, or deprecation warnings. It’s a low-risk way to modernize legacy systems while keeping costs down (MIT license, minimal overhead). Trade-off: Limited to Symfony 2, but we can phase it out during our next major upgrade."

To Engineering: *"This is a Symfony 2-specific way to inject pre/post controller hooks via route config (no code changes). Example:

# config/routes.yml
my_route:
    path: /example
    defaults: { _controller: AppController::action }
    callbacks:
        pre: [App\Callback\AuthCheck, 'validate']
        post: [App\Callback\Logger, 'logResponse']

Pros:

• No controller refactoring.
• Works with existing Symfony 2 apps.
• Config-driven (no PHP changes). Cons:
• Archived (last commit 2015)—vetted for our Symfony 2.8 use case.
• Not for complex logic (e.g., async tasks). Alternatives: If we’re upgrading, use Symfony’s EventDispatcher or middleware. For Laravel, use native middleware."*

To Developers: *"Need to add a quick pre-flight check or post-action logging to a controller? This bundle lets you define it in YAML:

callbacks:
    pre: [App\Service\RateLimiter, 'check']
    post: [App\Service\Metrics, 'record']

• How it works: Under the hood, it wraps Controller::handle() with your callbacks.
• Limitations:
  • No DI in callbacks (manually resolve services).
  • Symfony 2 only (won’t work with 3+).
• Migration path: Replace with Symfony’s EventDispatcher when ready."*