REST API Node

RESTful API Design for Node.js

Conventions and patterns for designing consistent, scalable REST APIs.

When to Use

• User is designing REST API endpoints
• User needs pagination, filtering, or sorting
• User asks about API versioning strategies
• User wants consistent response formats
• User mentions HATEOAS or API discoverability

Core Patterns

Resource Naming Conventions

Use plural nouns for collections. Nest sub-resources to express relationships. Keep URLs shallow (max 2 levels of nesting).

GET    /api/v1/users              -- List users
POST   /api/v1/users              -- Create user
GET    /api/v1/users/:id          -- Get user
PUT    /api/v1/users/:id          -- Replace user
PATCH  /api/v1/users/:id          -- Partial update
DELETE /api/v1/users/:id          -- Delete user

GET    /api/v1/users/:id/orders   -- List user's orders
POST   /api/v1/users/:id/orders   -- Create order for user

-- Actions that don't map to CRUD use verbs as sub-resources
POST   /api/v1/users/:id/activate
POST   /api/v1/orders/:id/cancel

Pagination

Return paginated results with metadata. Support both offset-based and cursor-based pagination.

import { Request, Response } from 'express'

interface PaginationQuery {
  page?: string
  limit?: string
  cursor?: string
}

async function listUsers(req: Request, res: Response) {
  const page = Math.max(1, parseInt(req.query.page as string) || 1)
  const limit = Math.min(100, Math.max(1, parseInt(req.query.limit as string) || 20))
  const offset = (page - 1) * limit

  const [users, total] = await Promise.all([
    db.user.findMany({ skip: offset, take: limit, orderBy: { createdAt: 'desc' } }),
    db.user.count(),
  ])

  const totalPages = Math.ceil(total / limit)
  const baseUrl = `${req.protocol}://${req.get('host')}${req.baseUrl}${req.path}`

  res.json({
    data: users,
    meta: { page, limit, total, totalPages },
    links: {
      self: `${baseUrl}?page=${page}&limit=${limit}`,
      first: `${baseUrl}?page=1&limit=${limit}`,
      last: `${baseUrl}?page=${totalPages}&limit=${limit}`,
      ...(page > 1 && { prev: `${baseUrl}?page=${page - 1}&limit=${limit}` }),
      ...(page < totalPages && { next: `${baseUrl}?page=${page + 1}&limit=${limit}` }),
    },
  })
}

Filtering and Sorting

Accept filters and sort via query parameters. Validate allowed fields.

const ALLOWED_FILTERS = new Set(['status', 'role', 'createdAfter', 'createdBefore'])
const ALLOWED_SORT_FIELDS = new Set(['name', 'email', 'createdAt'])

function parseFilters(query: Record<string, string>) {
  const where: Record<string, unknown> = {}

  if (query.status && ALLOWED_FILTERS.has('status')) {
    where.status = query.status
  }
  if (query.role && ALLOWED_FILTERS.has('role')) {
    where.role = query.role
  }
  if (query.createdAfter) {
    where.createdAt = { ...(where.createdAt as object), gte: new Date(query.createdAfter) }
  }
  if (query.createdBefore) {
    where.createdAt = { ...(where.createdAt as object), lte: new Date(query.createdBefore) }
  }

  return where
}

function parseSortParam(sort: string | undefined) {
  if (!sort) return { createdAt: 'desc' as const }

  const desc = sort.startsWith('-')
  const field = desc ? sort.slice(1) : sort

  if (!ALLOWED_SORT_FIELDS.has(field)) return { createdAt: 'desc' as const }
  return { [field]: desc ? 'desc' : 'asc' }
}

// Usage: GET /api/v1/users?status=active&sort=-createdAt&page=2
router.get('/users', asyncHandler(async (req, res) => {
  const where = parseFilters(req.query as Record<string, string>)
  const orderBy = parseSortParam(req.query.sort as string)
  // ... paginate with where and orderBy
}))

API Versioning

Use URL path versioning for simplicity and clarity. Each version is an explicit contract.

import { Router } from 'express'

const v1Router = Router()
v1Router.use('/users', userRoutesV1)
v1Router.use('/orders', orderRoutesV1)

const v2Router = Router()
v2Router.use('/users', userRoutesV2)
v2Router.use('/orders', orderRoutesV2)

app.use('/api/v1', v1Router)
app.use('/api/v2', v2Router)

Consistent Response Format

Use a uniform response envelope across all endpoints.

interface ApiResponse<T> {
  data: T
  meta?: {
    page: number
    limit: number
    total: number
    totalPages: number
  }
  links?: Record<string, string>
}

interface ApiErrorResponse {
  error: string
  details?: Record<string, string[]>
}

// Success
res.status(200).json({ data: user })

// Created
res.status(201).json({ data: newUser })

// No Content (delete)
res.status(204).end()

// Error
res.status(400).json({ error: 'Validation failed', details: { email: ['Invalid'] } })

Content Negotiation

Respond in the format the client requests via the Accept header.

function negotiateResponse(req: Request, res: Response, data: unknown) {
  res.format({
    'application/json': () => res.json({ data }),
    'text/csv': () => {
      const csv = convertToCsv(data)
      res.type('text/csv').send(csv)
    },
    default: () => res.status(406).json({ error: 'Not Acceptable' }),
  })
}

Anti-Patterns

• Using verbs in resource URLs -- /api/getUsers violates REST conventions. Use GET /api/users instead. HTTP methods convey the action.
• Returning 200 for errors -- Always use appropriate HTTP status codes. 200 means success. Use 4xx for client errors, 5xx for server errors.
• Unbounded list endpoints -- Always paginate collection endpoints. Returning all records causes memory exhaustion and slow responses.
• Exposing database IDs or internal structure -- Use UUIDs instead of sequential IDs. Do not leak table names or column names in error messages.
• Inconsistent response formats -- Sometimes returning { user: ... }, sometimes { data: ... }. Pick one envelope format and use it everywhere.

Quick Reference

HTTP Methods:
  GET     -- Read (idempotent, safe)
  POST    -- Create (not idempotent)
  PUT     -- Replace (idempotent)
  PATCH   -- Partial update (idempotent)
  DELETE  -- Remove (idempotent)

Status Codes:
  200 OK              -- Success
  201 Created         -- Resource created
  204 No Content      -- Successful delete
  400 Bad Request     -- Validation error
  401 Unauthorized    -- Missing/invalid auth
  403 Forbidden       -- Insufficient permissions
  404 Not Found       -- Resource doesn't exist
  409 Conflict        -- Duplicate/conflict
  429 Too Many Reqs   -- Rate limited
  500 Internal Error  -- Server bug

Query patterns:
  ?page=2&limit=20           -- Pagination
  ?sort=-createdAt           -- Sort desc
  ?status=active&role=admin  -- Filters
  ?fields=id,name,email      -- Sparse fields