backend-patterns
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ChineseBackend Development Patterns
后端开发模式
Backend architecture patterns, API design, database optimization, and server-side best practices for Node.js, Express, and Next.js API routes.
针对Node.js、Express和Next.js API路由的后端架构模式、API设计、数据库优化以及服务端最佳实践。
API Design Patterns
API设计模式
RESTful API Structure
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=0typescript
// ✅ 基于资源的URL
GET /api/markets # 列出资源
GET /api/markets/:id # 获取单个资源
POST /api/markets # 创建资源
PUT /api/markets/:id # 替换资源
PATCH /api/markets/:id # 更新资源
DELETE /api/markets/:id # 删除资源
// ✅ 用于筛选、排序、分页的查询参数
GET /api/markets?status=active&sort=volume&limit=20&offset=0Repository Pattern
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...
}typescript
// 抽象数据访问逻辑
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
}
// 其他方法...
}Service Layer Pattern
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
}
}typescript
// 业务逻辑与数据访问分离
class MarketService {
constructor(private marketRepo: MarketRepository) {}
async searchMarkets(query: string, limit: number = 10): Promise<Market[]> {
// 业务逻辑
const embedding = await generateEmbedding(query)
const results = await this.vectorSearch(embedding, limit)
// 获取完整数据
const markets = await this.marketRepo.findByIds(results.map(r => r.id))
// 按相似度排序
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) {
// 向量搜索实现
}
}Middleware Pattern
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
})typescript
// 请求/响应处理流水线
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' })
}
}
}
// 使用示例
export default withAuth(async (req, res) => {
// 处理函数可以访问req.user
})Database Patterns
数据库模式
Query Optimization
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('*')typescript
// ✅ 好的做法:仅选择需要的列
const { data } = await supabase
.from('markets')
.select('id, name, status, volume')
.eq('status', 'active')
.order('volume', { ascending: false })
.limit(10)
// ❌ 不好的做法:选择所有列
const { data } = await supabase
.from('markets')
.select('*')N+1 Query Prevention
N+1查询预防
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)
})typescript
// ❌ 不好的做法:N+1查询问题
const markets = await getMarkets()
for (const market of markets) {
market.creator = await getUser(market.creator_id) // N次查询
}
// ✅ 好的做法:批量获取
const markets = await getMarkets()
const creatorIds = markets.map(m => m.creator_id)
const creators = await getUsers(creatorIds) // 1次查询
const creatorMap = new Map(creators.map(c => [c.id, c]))
markets.forEach(market => {
market.creator = creatorMap.get(market.creator_id)
})Transaction Pattern
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 $$
BEGIN
-- Start transaction automatically
INSERT INTO markets VALUES (market_data);
INSERT INTO positions VALUES (position_data);
RETURN jsonb_build_object('success', true);
EXCEPTION
WHEN OTHERS THEN
-- Rollback happens automatically
RETURN jsonb_build_object('success', false, 'error', SQLERRM);
END;
$$;typescript
async function createMarketWithPosition(
marketData: CreateMarketDto,
positionData: CreatePositionDto
) {
// 使用Supabase事务
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
}
// Supabase中的SQL函数
CREATE OR REPLACE FUNCTION create_market_with_position(
market_data jsonb,
position_data jsonb
)
RETURNS jsonb
LANGUAGE plpgsql
AS $$
BEGIN
-- 自动开启事务
INSERT INTO markets VALUES (market_data);
INSERT INTO positions VALUES (position_data);
RETURN jsonb_build_object('success', true);
EXCEPTION
WHEN OTHERS THEN
-- 自动回滚
RETURN jsonb_build_object('success', false, 'error', SQLERRM);
END;
$$;Caching Strategies
缓存策略
Redis Caching Layer
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:${id}`)
}
}typescript
class CachedMarketRepository implements MarketRepository {
constructor(
private baseRepo: MarketRepository,
private redis: RedisClient
) {}
async findById(id: string): Promise<Market | null> {
// 优先检查缓存
const cached = await this.redis.get(`market:${id}`)
if (cached) {
return JSON.parse(cached)
}
// 缓存未命中 - 从数据库获取
const market = await this.baseRepo.findById(id)
if (market) {
// 缓存5分钟
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 Pattern
旁路缓存模式
typescript
async function getMarketWithCache(id: string): Promise<Market> {
const cacheKey = `market:${id}`
// Try cache
const cached = await redis.get(cacheKey)
if (cached) return JSON.parse(cached)
// Cache miss - fetch from DB
const market = await db.markets.findUnique({ where: { id } })
if (!market) throw new Error('Market not found')
// Update cache
await redis.setex(cacheKey, 300, JSON.stringify(market))
return market
}typescript
async function getMarketWithCache(id: string): Promise<Market> {
const cacheKey = `market:${id}`
// 尝试从缓存获取
const cached = await redis.get(cacheKey)
if (cached) return JSON.parse(cached)
// 缓存未命中 - 从数据库获取
const market = await db.markets.findUnique({ where: { id } })
if (!market) throw new Error('Market not found')
// 更新缓存
await redis.setex(cacheKey, 300, JSON.stringify(market))
return market
}Error Handling Patterns
错误处理模式
Centralized Error Handler
集中式错误处理器
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)
}
}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 })
}
// 记录非预期错误
console.error('Unexpected error:', error)
return NextResponse.json({
success: false,
error: 'Internal server error'
}, { status: 500 })
}
// 使用示例
export async function GET(request: Request) {
try {
const data = await fetchData()
return NextResponse.json({ success: true, data })
} catch (error) {
return errorHandler(error, request)
}
}Retry with Exponential Backoff
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())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) {
// 指数退避:1s, 2s, 4s
const delay = Math.pow(2, i) * 1000
await new Promise(resolve => setTimeout(resolve, delay))
}
}
}
throw lastError!
}
// 使用示例
const data = await fetchWithRetry(() => fetchFromAPI())Authentication & Authorization
身份认证与授权
JWT Token Validation
JWT令牌校验
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 })
}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)
}
// 在API路由中使用
export async function GET(request: Request) {
const user = await requireAuth(request)
const data = await getDataForUser(user.userId)
return NextResponse.json({ success: true, data })
}Role-Based Access Control
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 async (request: Request) => {
const user = await requireAuth(request)
if (!hasPermission(user, permission)) {
throw new ApiError(403, 'Insufficient permissions')
}
return user
}
}
// Usage
export const DELETE = requirePermission('delete')(async (request: Request) => {
// Handler with permission check
})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 async (request: Request) => {
const user = await requireAuth(request)
if (!hasPermission(user, permission)) {
throw new ApiError(403, 'Insufficient permissions')
}
return user
}
}
// 使用示例
export const DELETE = requirePermission('delete')(async (request: Request) => {
// 带权限校验的处理函数
})Rate Limiting
限流
Simple In-Memory Rate Limiter
简单内存限流器
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
}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) || []
// 移除时间窗口外的旧请求
const recentRequests = requests.filter(time => now - time < windowMs)
if (recentRequests.length >= maxRequests) {
return false // 超出限流阈值
}
// 记录当前请求
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) // 每分钟100次请求
if (!allowed) {
return NextResponse.json({
error: 'Rate limit exceeded'
}, { status: 429 })
}
// 继续处理请求
}Background Jobs & Queues
后台任务与队列
Simple Queue Pattern
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' })
}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> {
// 任务执行逻辑
}
}
// 用于索引市场的使用示例
interface IndexJob {
marketId: string
}
const indexQueue = new JobQueue<IndexJob>()
export async function POST(request: Request) {
const { marketId } = await request.json()
// 添加到队列而不是阻塞请求
await indexQueue.add({ marketId })
return NextResponse.json({ success: true, message: 'Job queued' })
}Logging & Monitoring
日志与监控
Structured Logging
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 })
}
}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()
// 使用示例
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 })
}
}Best Practices
最佳实践
- Use patterns appropriate to your scale: Start simple, add complexity only when needed
- Separate concerns: Keep business logic, data access, and API layers separate
- Handle errors consistently: Use centralized error handling
- Cache strategically: Cache frequently accessed, slowly changing data
- Log structured data: Use structured logging for better observability
- Secure by default: Always validate input, authenticate requests, and authorize actions
- Optimize queries: Avoid N+1 queries, select only needed columns
- Use transactions: For operations that must succeed or fail together
- Rate limit: Protect your APIs from abuse
- Monitor and measure: Track performance and errors
Remember: Backend patterns enable scalable, maintainable server-side applications. Choose patterns that fit your complexity level.
- 使用符合你规模的模式:从简单开始,仅在需要时增加复杂度
- 关注点分离:将业务逻辑、数据访问和API层分开
- 一致的错误处理:使用集中式错误处理
- 策略性缓存:缓存访问频繁、变更缓慢的数据
- 记录结构化数据:使用结构化日志提升可观测性
- 默认安全:始终验证输入、对请求做身份认证、对操作做授权
- 优化查询:避免N+1查询,仅选择需要的列
- 使用事务:处理必须同时成功或失败的操作
- 限流:保护你的API不被滥用
- 监控与度量:追踪性能和错误
记住:后端模式助力实现可扩展、可维护的服务端应用。选择符合你复杂度水平的模式即可。