Presentation Adapters¶

Request Adapter¶

RequestAdapter[RawRequest, UseCaseInput] translates raw transport requests into typed use-case input.

Responsibilities:
- Deserialize transport formats (JSON, form data, query strings)
- Extract and normalize headers, parameters, and body
- Return a typed DTO or command for the use case

Framework-aware. Stateless — produces a value, no side effects.

When to use (RequestAdapter)¶

Implement RequestAdapter for each transport your system supports — HTTP requests, CLI arguments, message queue payloads. The protocol is generic; your implementation handles the specific deserialization.

Response Adapter¶

ResponseAdapter[UseCaseOutput, RawResponse] translates application output into transport responses.

Two methods:
- adapt(output) — successful use-case output → transport response
- adapt_error(view_model) — ErrorViewModel → transport error response

Handles both happy and error paths. Produces the final transport response.

Presentation Adapter¶

PresentationAdapter orchestrates the full request/response lifecycle:

1. RequestAdapter.adapt(raw)  → use-case input
2. UseCase.execute(input)     → output or Result
3a. Success  → ResponseAdapter.adapt(output)
3b. Err/Exception → ErrorPresenter → ErrorStatusCodeMapper → ResponseAdapter.adapt_error()

Key design:

Handles both Result.Err and raised exceptions. Callers choose their style.
When ErrorPresenter is None, exceptions propagate unchanged.

See Error Handling for how errors are converted and rendered.