---
id: api-rest-best-practices
title: REST Best Practices — Resource / 상태코드 / HATEOAS
category: Coding
status: draft
source_trust_level: B
verification_status: conceptual
created_at: 2026-05-09
updated_at: 2026-05-09
tags: [api, rest, http, vibe-coding]
tech_stack: { language: "TS", applicable_to: ["Backend"] }
applied_in: []
aliases: [REST, RESTful, HTTP API, resource-oriented, CRUD, status code]
---

# REST Best Practices

> 일관된 REST = 사용자 학습 비용↓. **명사 resource + HTTP method + 표준 status code**. JSON-API / RFC 7807 / OpenAPI 같이.

## 📖 핵심 개념
- Resource: 명사 (`/orders`, `/users/:id/orders`).
- HTTP method: GET / POST / PUT / PATCH / DELETE.
- Status code: 의미 있게.
- Idempotency: GET / PUT / DELETE = idempotent.

## 💻 코드 패턴

### URL 구조
```
✅ Good
GET    /orders                  # list
GET    /orders/42               # single
POST   /orders                  # create
PUT    /orders/42               # full update
PATCH  /orders/42               # partial update
DELETE /orders/42               # delete

GET    /users/u1/orders         # nested (user 의 orders)

❌ Bad
GET /getOrders
POST /createOrder
GET /orders?action=delete
```

### Status code
```
2xx Success:
  200 OK            - GET, PATCH, PUT
  201 Created       - POST (with Location header)
  202 Accepted      - async (job queued)
  204 No Content    - DELETE, PUT (no body)

4xx Client error:
  400 Bad Request   - validation failed
  401 Unauthorized  - 인증 필요
  403 Forbidden     - 권한 부족
  404 Not Found     - 자원 없음
  409 Conflict      - 중복 / version mismatch
  422 Unprocessable - semantic error
  429 Too Many      - rate limit

5xx Server:
  500 Internal      - 모르는 에러
  502 Bad Gateway   - upstream 에러
  503 Unavailable   - 일시 down
  504 Gateway Timeout
```

### POST → 201 + Location
```ts
app.post('/orders', async (req, res) => {
  const order = await createOrder(req.body);
  res.status(201)
     .location(`/orders/${order.id}`)
     .json(order);
});
```

### Pagination
```
GET /orders?limit=20&cursor=abc
→ 응답:
{
  "data": [...],
  "pagination": {
    "next_cursor": "xyz",
    "has_more": true
  }
}
```

또는 `Link` 헤더:
```
Link: <...?cursor=xyz>; rel="next", <...?cursor=first>; rel="first"
```

→ Cursor pagination 권장 (offset 보다 안정).

### Filtering / sorting / fields
```
GET /orders?status=paid&user_id=u1
GET /orders?sort=-createdAt
GET /orders?fields=id,status,total       # sparse fieldset
GET /orders?include=items,customer       # related
```

### Versioning
```
URL:        /v1/orders, /v2/orders
Header:     Accept: application/vnd.acme.v2+json
Query:      /orders?version=2

→ URL 가 명확하고 cache 친화. 권장.
```

### Error format (RFC 7807)
```ts
res.status(400).json({
  type: 'https://api.acme.com/errors/validation',
  title: 'Invalid input',
  status: 400,
  detail: 'Email must be valid',
  errors: [
    { path: 'email', message: 'invalid format' },
    { path: 'age', message: 'must be positive' }
  ],
  traceId: req.headers['x-request-id'],
});
```

→ 일관 error envelope.

### Idempotency
```
GET    : 항상 idempotent
PUT    : idempotent (전체 교체)
DELETE : idempotent
PATCH  : 보통 X (depends)
POST   : X (단, idempotency-key header 로)
```

```
POST /payments
Idempotency-Key: 550e8400-...
```

→ 같은 key 두 번 = 한 번만 처리.

### HATEOAS (controversial)
```json
{
  "id": 42,
  "status": "shipped",
  "_links": {
    "self": "/orders/42",
    "cancel": "/orders/42/cancel",
    "shipment": "/shipments/99"
  }
}
```

→ Client 가 URL hardcode X. 그러나 거의 안 씀 — overkill.

### Authentication
```
Authorization: Bearer <token>     # 표준
또는
Authorization: Basic <base64>     # legacy
또는
X-API-Key: <key>                  # custom (덜 권장)
```

### Rate limit headers
```
X-RateLimit-Limit: 1000
X-RateLimit-Remaining: 950
X-RateLimit-Reset: 1715238000
Retry-After: 30                   # 429 시
```

### Cache headers
```
Cache-Control: public, max-age=60
ETag: "abc123"
Last-Modified: ...

# Client 가 다음 요청
If-None-Match: "abc123"
→ 304 Not Modified (body 없음)
```

### Date / time
```
ISO 8601 UTC:
"createdAt": "2026-05-09T10:30:00.000Z"

❌ "createdAt": "May 9, 2026 10:30 AM"
❌ "createdAt": 1715238000  # epoch — 의미 모름
```

### Money
```json
{
  "amount": "1234.56",       // string, 정확
  "currency": "USD"
}
```

→ Float 사용 X. Decimal string.

### Bulk
```
POST /orders/bulk
Body: [order1, order2, ...]

→ 부분 실패 처리:
{
  "results": [
    { "status": "ok", "id": "o1" },
    { "status": "error", "error": {...} }
  ]
}
```

## 🤔 의사결정 기준
| 상황 | 권장 |
|---|---|
| Public API | REST + OpenAPI |
| Internal microservice | gRPC / GraphQL / REST 어떤 것도 |
| 복잡 query | GraphQL |
| Realtime | WebSocket / SSE |
| 강 type | tRPC (TS only) |
| File upload | REST (multipart/form-data) |
| Bulk | POST /resource/bulk |

## ❌ 안티패턴
- **GET 으로 변경**: 위험 (브라우저 prefetch 등).
- **Verb URL (`/createOrder`)**: 명사 resource.
- **모두 200 + body 안 error**: status code 의미 없음.
- **500 으로 모든 에러**: 의미 잃음.
- **PII URL**: log leak. body 또는 header.
- **시간 하드코딩 timezone**: UTC ISO.
- **versioning 없음**: breaking change 시 panic.
- **Pagination 없는 list**: 1만 row 반환.

## 🤖 LLM 활용 힌트
- 명사 resource + HTTP method + 표준 status.
- RFC 7807 error envelope.
- OpenAPI 로 schema 명시.

## 🔗 관련 문서
- [[API_OpenAPI_Spec]]
- [[API_Error_Format_RFC7807]]
- [[API_Pagination_Patterns]]
- [[API_Versioning_Strategies]]
