介绍
# Backend Development Patterns
用于构建可扩展服务器端应用程序的后端架构模式和最佳实践。
## API 设计模式
### RESTful API 结构
```typescript // ✅ Resource-based URLs GET /api/markets # List resources GET /api/markets/:id # Get single resource POST /api/markets # Create resource PUT /api/markets/:id # Replace resource PATCH /api/markets/:id # Update resource DELETE /api/markets/:id # Delete resource
// ✅ Query parameters for filtering, sorting, pagination GET /api/markets?status=active&sort=volume&limit=20&offset=0 ```
### 仓储模式
```typescript // Abstract data access logic interface MarketRepository { findAll(filters?: MarketFilters): Promise<Market[]> findById(id: string): Promise<Market | null> create(data: CreateMarketDto): Promise<Market> update(id: string, data: UpdateMarketDto): Promise<Market> delete(id: string): Promise<void> }
class SupabaseMarketRepository implements MarketRepository { async findAll(filters?: MarketFilters): Promise<Market[]> { let query = supabase.from('markets').select('*')
if (filters?.status) { query = query.eq('status', filters.status) }
if (filters?.limit) { query = query.limit(filters.limit) }
const { data, error } = await query
if (error) throw new Error(error.message) return data }
// Other methods... } ```
### 服务层模式
```typescript // Business logic separated from data access class MarketService { constructor(private marketRepo: MarketRepository) {}
async searchMarkets(query: string, limit: number = 10): Promise<Market[]> { // Business logic const embedding = await generateEmbedding(query) const results = await this.vectorSearch(embedding, limit)
// Fetch full data const markets = await this.marketRepo.findByIds(results.map(r => r.id))
// Sort by similarity return markets.sort((a, b) => { const scoreA = results.find(r => r.id === a.id)?.score || 0 const scoreB = results.find(r => r.id === b.id)?.score || 0 return scoreA - scoreB }) }
private async vectorSearch(embedding: number[], limit: number) { // Vector search implementation } } ```
### 中间件模式
```typescript // Request/response processing pipeline export function withAuth(handler: NextApiHandler): NextApiHandler { return async (req, res) => { const token = req.headers.authorization?.replace('Bearer ', '')
if (!token) { return res.status(401).json({ error: 'Unauthorized' }) }
try { const user = await verifyToken(token) req.user = user return handler(req, res) } catch (error) { return res.status(401).json({ error: 'Invalid token' }) } } }
// Usage export default withAuth(async (req, res) => { // Handler has access to req.user }) ```
## 数据库模式
### 查询优化
```typescript // ✅ GOOD: Select only needed columns const { data } = await supabase .from('markets') .select('id, name, status, volume') .eq('status', 'active') .order('volume', { ascending: false }) .limit(10)
// ❌ BAD: Select everything const { data } = await supabase .from('markets') .select('*') ```
### N+1 查询防范
```typescript // ❌ BAD: N+1 query problem const markets = await getMarkets() for (const market of markets) { market.creator = await getUser(market.creator_id) // N queries }
// ✅ GOOD: Batch fetch const markets = await getMarkets() const creatorIds = markets.map(m => m.creator_id) const creators = await getUsers(creatorIds) // 1 query const creatorMap = new Map(creators.map(c => [c.id, c]))
markets.forEach(market => { market.creator = creatorMap.get(market.creator_id) }) ```
### 事务模式
```typescript async function createMarketWithPosition( marketData: CreateMarketDto, positionData: CreatePositionDto ) { // Use Supabase transaction const { data, error } = await supabase.rpc('create_market_with_position', { market_data: marketData, position_data: positionData })
if (error) throw new Error('Transaction failed') return data }
// SQL function in Supabase CREATE OR REPLACE FUNCTION create_market_with_position( market_data jsonb, position_data jsonb ) RETURNS jsonb LANGUAGE plpgsql AS $ BEGIN -- Start transaction automatically INSERT INTO markets VALUES (market_data); INSERT INTO positions VALUES (position_data); RETURN jsonb_build_object('success', true); EXCEPTION WHEN OTHERS THEN -- Rollback happens automatically RETURN jsonb_build_object('success', false, 'error', SQLERRM); END; $; ```
## 缓存策略
### Redis 缓存层
```typescript class CachedMarketRepository implements MarketRepository { constructor( private baseRepo: MarketRepository, private redis: RedisClient ) {}
async findById(id: string): Promise<Market | null> { // Check cache first const cached = await this.redis.get(`market:${id}`)
if (cached) { return JSON.parse(cached) }
// Cache miss - fetch from database const market = await this.baseRepo.findById(id)
if (market) { // Cache for 5 minutes await this.redis.setex(`market:${id}`, 300, JSON.stringify(market)) }
return market }
async invalidateCache(id: string): Promise<void> { await this.redis.del(`market:${id}`) } } ```
### Cache-Aside 模式
```typescript async function getMarketWithCache(id: string): Promise<Market> { const cacheKey = `market:${id}`
// Try cache const cached = await redis.get(cacheKey) if (cached) return JSON.parse(cached)
// Cache miss - fetch from DB const market = await db.markets.findUnique({ where: { id } })
if (!market) throw new Error('Market not found')
// Update cache await redis.setex(cacheKey, 300, JSON.stringify(market))
return market } ```
## 错误处理模式
### 集中式错误处理程序
```typescript class ApiError extends Error { constructor( public statusCode: number, public message: string, public isOperational = true ) { super(message) Object.setPrototypeOf(this, ApiError.prototype) } }
export function errorHandler(error: unknown, req: Request): Response { if (error instanceof ApiError) { return NextResponse.json({ success: false, error: error.message }, { status: error.statusCode }) }
if (error instanceof z.ZodError) { return NextResponse.json({ success: false, error: 'Validation failed', details: error.errors }, { status: 400 }) }
// Log unexpected errors console.error('Unexpected error:', error)
return NextResponse.json({ success: false, error: 'Internal server error' }, { status: 500 }) }
// Usage export async function GET(request: Request) { try { const data = await fetchData() return NextResponse.json({ success: true, data }) } catch (error) { return errorHandler(error, request) } } ```
### 指数退避重试
```typescript async function fetchWithRetry<T>( fn: () => Promise<T>, maxRetries = 3 ): Promise<T> { let lastError: Error
for (let i = 0; i < maxRetries; i++) { try { return await fn() } catch (error) { lastError = error as Error
if (i < maxRetries - 1) { // Exponential backoff: 1s, 2s, 4s const delay = Math.pow(2, i) * 1000 await new Promise(resolve => setTimeout(resolve, delay)) } } }
throw lastError! }
// Usage const data = await fetchWithRetry(() => fetchFromAPI()) ```
## 身份验证与授权
### JWT 令牌验证
```typescript import jwt from 'jsonwebtoken'
interface JWTPayload { userId: string email: string role: 'admin' | 'user' }
export function verifyToken(token: string): JWTPayload { try { const payload = jwt.verify(token, process.env.JWT_SECRET!) as JWTPayload return payload } catch (error) { throw new ApiError(401, 'Invalid token') } }
export async function requireAuth(request: Request) { const token = request.headers.get('authorization')?.replace('Bearer ', '')
if (!token) { throw new ApiError(401, 'Missing authorization token') }
return verifyToken(token) }
// Usage in API route export async function GET(request: Request) { const user = await requireAuth(request)
const data = await getDataForUser(user.userId)
return NextResponse.json({ success: true, data }) } ```
### 基于角色的访问控制
```typescript type Permission = 'read' | 'write' | 'delete' | 'admin'
interface User { id: string role: 'admin' | 'moderator' | 'user' }
const rolePermissions: Record<User['role'], Permission[]> = { admin: ['read', 'write', 'delete', 'admin'], moderator: ['read', 'write', 'delete'], user: ['read', 'write'] }
export function hasPermission(user: User, permission: Permission): boolean { return rolePermissions[user.role].includes(permission) }
export function requirePermission(permission: Permission) { return (handler: (request: Request, user: User) => Promise<Response>) => { return async (request: Request) => { const user = await requireAuth(request)
if (!hasPermission(user, permission)) { throw new ApiError(403, 'Insufficient permissions') }
return handler(request, user) } } }
// Usage - HOF wraps the handler export const DELETE = requirePermission('delete')( async (request: Request, user: User) => { // Handler receives authenticated user with verified permission return new Response('Deleted', { status: 200 }) } ) ```
## 速率限制
### 简单内存速率限制器
```typescript class RateLimiter { private requests = new Map<string, number[]>()
async checkLimit( identifier: string, maxRequests: number, windowMs: number ): Promise<boolean> { const now = Date.now() const requests = this.requests.get(identifier) || []
// Remove old requests outside window const recentRequests = requests.filter(time => now - time < windowMs)
if (recentRequests.length >= maxRequests) { return false // Rate limit exceeded }
// Add current request recentRequests.push(now) this.requests.set(identifier, recentRequests)
return true } }
const limiter = new RateLimiter()
export async function GET(request: Request) { const ip = request.headers.get('x-forwarded-for') || 'unknown'
const allowed = await limiter.checkLimit(ip, 100, 60000) // 100 req/min
if (!allowed) { return NextResponse.json({ error: 'Rate limit exceeded' }, { status: 429 }) }
// Continue with request } ```
## 后台任务与队列
### 简单队列模式
```typescript class JobQueue<T> { private queue: T[] = [] private processing = false
async add(job: T): Promise<void> { this.queue.push(job)
if (!this.processing) { this.process() } }
private async process(): Promise<void> { this.processing = true
while (this.queue.length > 0) { const job = this.queue.shift()!
try { await this.execute(job) } catch (error) { console.error('Job failed:', error) } }
this.processing = false }
private async execute(job: T): Promise<void> { // Job execution logic } }
// Usage for indexing markets interface IndexJob { marketId: string }
const indexQueue = new JobQueue<IndexJob>()
export async function POST(request: Request) { const { marketId } = await request.json()
// Add to queue instead of blocking await indexQueue.add({ marketId })
return NextResponse.json({ success: true, message: 'Job queued' }) } ```
## 日志记录与监控
### 结构化日志
```typescript interface LogContext { userId?: string requestId?: string method?: string path?: string [key: string]: unknown }
class Logger { log(level: 'info' | 'warn' | 'error', message: string, context?: LogContext) { const entry = { timestamp: new Date().toISOString(), level, message, ...context }
console.log(JSON.stringify(entry)) }
info(message: string, context?: LogContext) { this.log('info', message, context) }
warn(message: string, context?: LogContext) { this.log('warn', message, context) }
error(message: string, error: Error, context?: LogContext) { this.log('error', message, { ...context, error: error.message, stack: error.stack }) } }
const logger = new Logger()
// Usage export async function GET(request: Request) { const requestId = crypto.randomUUID()
logger.info('Fetching markets', { requestId, method: 'GET', path: '/api/markets' })
try { const markets = await fetchMarkets() return NextResponse.json({ success: true, data: markets }) } catch (error) { logger.error('Failed to fetch markets', error as Error, { requestId }) return NextResponse.json({ error: 'Internal error' }, { status: 500 }) } } ```
**请记住**：后端模式能够实现可扩展、可维护的服务器端应用程序。请选择适合您复杂度级别的模式。