be-elixir

To implement a Phoenix backend API, use this Skill to generate Ecto schemas, context modules, and controllers from an OpenAPI contract. It enforces contract-first principles, data validation via changesets, and idiomatic context-based design.

The best way to structure Elixir business logic is using context-based design. Group related functions into dedicated context modules that interact with Ecto schemas, encapsulating data persistence and business rules away from the controller layer.

You test API endpoints and business logic in Elixir using ExUnit. Write comprehensive tests covering context functions and controller actions to validate changesets, data persistence, and OTP patterns for robust backend verification.

Yes, Ecto changeset validation works seamlessly with Phoenix context modules. Context functions create and apply changesets to validate data before persistence, ensuring API endpoints receive structurally correct data and return appropriate validation errors.

Use OTP patterns in Elixir backend services when managing long-running processes, stateful GenServers, or supervision trees. They provide fault tolerance and scalability for background tasks and concurrent operations beyond standard request-response cycles.

While you can build APIs in pure Elixir, Phoenix provides essential conventions like Ecto for data persistence, context-based design, and controller structures. Developing without it requires manually building these scalable, maintainable architectural layers.