| name | backend |
| description | Use for server-side tasks: implementing APIs, services, business logic, authentication, and middleware with any backend stack (Python, TypeScript, Go, Java, Rust, etc.). |
Backend Development
When to use
- Building REST, GraphQL, or gRPC APIs
- Implementing business logic, services, or use cases
- Configuring server, middleware, or authentication
- Working with ORMs, database access, or caching
- Adding validation, serialization, or error handling
- API versioning, documentation, or testing
API design patterns
REST — semantic endpoints
GET /api/v1/users # list (paginated)
POST /api/v1/users # create
GET /api/v1/users/:id # retrieve
PUT /api/v1/users/:id # replace
PATCH /api/v1/users/:id # partial update
DELETE /api/v1/users/:id # delete
GraphQL — one endpoint
- Queries for reads, mutations for writes
- Input types for mutations (not raw scalars)
- Error codes in
extensions field
- DataLoader pattern to batch & cache (avoid N+1)
gRPC — typed contracts
.proto files as source of truth- Unary for request/response, server streaming, client streaming, bidirectional
- Errors via status codes (google.rpc)
Response format (REST)
Success
{
"data": { ... },
"meta": { "page": 1, "limit": 20, "total": 100 }
}
Error
{
"error": {
"code": "VALIDATION_ERROR",
"message": "Email is required",
"details": { "field": "email" }
}
}
Security checklist
Dependency injection
class UserService:
def __init__(self, repo: UserRepository, mailer: Mailer):
self.repo = repo
self.mailer = mailer
class UserService {
constructor(
private repo: UserRepository,
private mailer: Mailer
) {}
}
(DI enables testability — inject mocks in tests)
Useful patterns
Service layer
Route → Controller (parse + validate) → Service (business logic) → Repository (data access)
Unit of Work
Wrap multiple DB operations in a transaction. Pass session/connection through the call chain.
Result type
type Result<T, E = Error> = { ok: true; value: T } | { ok: false; error: E };
(Explicit error handling instead of try/catch everywhere)
Resources
