phoenix-patterns

Phoenix contexts provide boundary-driven architecture for domain logic, while controllers handle HTTP requests with thin, focused actions. Pair fat contexts containing business logic with clean controllers that delegate to contexts, enabling maintainable separation of concerns across your web application.

Use plug pipelines and action_fallback to enforce authentication and authorization consistently. Define reusable plugs that check credentials, compose them into named pipelines, and attach pipelines to route groups so policies apply uniformly across API and HTML interfaces without repetition.

Group related routes using Phoenix's scope and resources macros, then compose plug pipelines to handle cross-cutting concerns like authentication and content negotiation. This structure lets you apply middleware consistently across route groups while keeping controllers thin and focused.

Yes, action_fallback centralizes error handling by routing failed controller actions to a single handler function. Define fallback clauses for common error tuples, then attach action_fallback to your controller so all actions automatically convert errors to appropriate HTTP responses.

Contexts isolate domain logic and business rules into reusable modules independent of HTTP concerns, while controllers translate HTTP requests into context calls and format responses. This separation makes contexts testable without web dependencies and keeps controllers simple routing layers.