Retrofit Networking

---
name: Flutter Networking (Retrofit & Dio)
description: HTTP networking standards using Dio and Retrofit with Auth interceptors.
metadata:
  labels: [networking, retrofit, dio]
  triggers:
    files: ['**/data_sources/**', '**/api/**']
    keywords: [Retrofit, Dio, RestClient, GET, POST, Interceptor, refreshing]
---

# Retrofit & Dio Networking

## **Priority: P0 (CRITICAL)**

Type-safe REST API communication using `Dio` and `Retrofit`.

## Structure

```text
infrastructure/
├── data_sources/
│   ├── remote/ # Retrofit abstract classes
│   └── local/ # Cache/Storage
└── network/
    ├── dio_client.dart # Custom Dio setup
    └── interceptors/ # Auth, Logging, Cache
```

## Implementation Guidelines

- **Retrofit Clients**: Define abstract classes with `@RestApi()`. Use standard HTTP annotations (`@GET`, `@POST`).
- **DTOs (Data Transfer Objects)**: Use `@freezed` and `json_serializable` for all response/request bodies.
- **Mapping**: Data sources MUST map DTOs to Domain Entities (e.g., `userDto.toDomain()`).
- **AuthInterceptor**: Logic for `Authorization: Bearer <token>` injection in `onRequest`.
- **Token Refresh**: Handle `401 Unauthorized` in `onError` by locking Dio, refreshing, and retrying.
- **Failures**: Map `DioException` to custom `Failure` objects (ServerFailure, NetworkFailure).

## Anti-Patterns

- **No Manual JSON Parsing**: Do not use `jsonDecode(response.body)`; use Retrofit's generated mappers.
- **No Global Dio**: Do not use a static global Dio instance; use dependency injection.
- **No Try-Catch in API**: Do not put `try-catch` inside the Retrofit interface methods.

## Reference & Examples

For RestClient definitions and Auth Interceptor implementation:
See [references/REFERENCE.md](references/REFERENCE.md).

## Related Topics

feature-based-clean-architecture | error-handling