codeigniter-knowledgelisted

# CodeIgniter Knowledge Base Quick reference for CodeIgniter 4 framework patterns and PHP implementation guidelines. CodeIgniter 4 is a complete rewrite of the framework, built for PHP 8.1+ with namespaces, autoloading, and a modern MVC architecture. It remains lightweight and fast while providing the tools needed for professional application development. ## Core Principles ### MVC Architecture ``` Request → index.php → Bootstrap → Routing → Filters (before) → Controller → Service/Model → View → Filters (after) → Response ``` **Key principles:** - Lightweight core with minimal overhead - HMVC-capable via modules (app/Modules/) - Services container for dependency management - Filters as middleware equivalent - Entity classes for data hydration ## Quick Checklists ### DDD-Compatible CI4 Project - [ ] Domain logic extracted from Models into Domain layer - [ ] Repository interfaces defined in Domain, implemented in Infrastructure - [ ] Value Objects used instead of primitive types for domain concepts - [ ] CI4 Models used only as persistence adapters - [ ] Services registered in Config\Services for dependency injection - [ ] Business rules not in Controllers or Filters - [ ] Domain Events dispatched through domain `EventDispatcherInterface` port (not CI4 Events directly) - [ ] Input validation at Controller level (not in Domain) - [ ] Shield Groups/Permissions used only at Filter/Route level; Domain uses Specifications - [ ] Queue job handlers delegate to Application