loulanyue 後端開發模式
用於可擴展伺服器端應用程式的後端架構模式和最佳實務。
API 設計模式
RESTful API 結構
// ✅ 基於資源的 URL
GET /api/markets # 列出資源
GET /api/markets/:id # 取得單一資源
POST /api/markets # 建立資源
PUT /api/markets/:id # 替換資源
PATCH /api/markets/:id # 更新資源
DELETE /api/markets/:id # 刪除資源
// ✅ 用於過濾、排序、分頁的查詢參數
GET /api/markets?status=active&sort=volume&limit=20&offset=0
Repository 模式
// 抽象資料存取邏輯
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 層模式
// 業務邏輯與資料存取分離
class MarketService {
constructor(private marketRepo: MarketRepository) {}
async searchMarkets(query: string, limit: number = 10): Promise<Market[]> {
// 業務邏輯
const embedding = await generateEmbedding(query)
const results = await this.vectorSearch(embedding, limit)
// 取得完整資料
const markets = await this.marketRepo.findByIds(results.map(r => r.id))
// 依相似度排序
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) {
// 向量搜尋實作
}
}
Middleware 模式
// 請求/回應處理流水線
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' })
}
}
}
// 使用方式
export default withAuth(async (req, res) => {
// Handler 可存取 req.user
})
資料庫模式
查詢優化
// ✅ 良好：只選擇需要的欄位
const { data } = await supabase
.from('markets')
.select('id, name, status, volume')
.eq('status', 'active')
.order('volume', { ascending: false })
.limit(10)
// ❌ 不良：選擇所有欄位
const { data } = await supabase
.from('markets')
.select('*')
N+1 查詢問題預防
// ❌ 不良：N+1 查詢問題
const markets = await getMarkets()
for (const market of markets) {
market.creator = await getUser(market.creator_id) // N 次查詢
}
// ✅ 良好：批次取得
const markets = await getMarkets()
const creatorIds = markets.map(m => m.creator_id)
const creators = await getUsers(creatorIds) // 1 次查詢
const creatorMap = new Map(creators.map(c => [c.id, c]))
markets.forEach(market => {
market.creator = creatorMap.get(market.creator_id)
})
Transaction 模式
async function createMarketWithPosition(
marketData: CreateMarketDto,
positionData: CreatePositionDto
) {
// 使用 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
}
// Supabase 中的 SQL 函式
CREATE OR REPLACE FUNCTION create_market_with_position(
market_data jsonb,
position_data jsonb
)
RETURNS jsonb
LANGUAGE plpgsql
AS $$
BEGIN
-- 自動開始 transaction
INSERT INTO markets VALUES (market_data);
INSERT INTO positions VALUES (position_data);
RETURN jsonb_build_object('success', true);
EXCEPTION
WHEN OTHERS THEN
-- 自動 rollback
RETURN jsonb_build_object('success', false, 'error', SQLERRM);
END;
$$;
快取策略
Redis 快取層
class CachedMarketRepository implements MarketRepository {
constructor(
private baseRepo: MarketRepository,
private redis: RedisClient
) {}
async findById(id: string): Promise<Market | null> {
// 先檢查快取
const cached = await this.redis.get(`market:${id}`)
if (cached) {
return JSON.parse(cached)
}
// 快取未命中 - 從資料庫取得
const market = await this.baseRepo.findById(id)
if (market) {
// 快取 5 分鐘
await this.redis.setex(`market:${id}`, 300, JSON.stringify(market))
}
return market
}
async invalidateCache(id: string): Promise<void> {
await this.redis.del(`market:${id}`)
}
}
Cache-Aside 模式
async function getMarketWithCache(id: string): Promise<Market> {
const cacheKey = `market:${id}`
// 嘗試快取
const cached = await redis.get(cacheKey)
if (cached) return JSON.parse(cached)
// 快取未命中 - 從資料庫取得
const market = await db.markets.findUnique({ where: { id } })
if (!market) throw new Error('Market not found')
// 更新快取
await redis.setex(cacheKey, 300, JSON.stringify(market))
return market
}
錯誤處理模式
集中式錯誤處理器
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 })
}
// 記錄非預期錯誤
console.error('Unexpected error:', error)
return NextResponse.json({
success: false,
error: 'Internal server error'
}, { status: 500 })
}
// 使用方式
export async function GET(request: Request) {
try {
const data = await fetchData()
return NextResponse.json({ success: true, data })
} catch (error) {
return errorHandler(error, request)
}
}
指數退避重試
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) {
// 指數退避：1s, 2s, 4s
const delay = Math.pow(2, i) * 1000
await new Promise(resolve => setTimeout(resolve, delay))
}
}
}
throw lastError!
}
// 使用方式
const data = await fetchWithRetry(() => fetchFromAPI())
認證與授權
JWT Token 驗證
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 })
}
基於角色的存取控制
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)
}
}
}
// 使用方式 - HOF 包裝 handler
export const DELETE = requirePermission('delete')(
async (request: Request, user: User) => {
// Handler 接收已驗證且具有已驗證權限的使用者
return new Response('Deleted', { status: 200 })
}
)
速率限制
簡單的記憶體速率限制器
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) || []
// 移除視窗外的舊請求
const recentRequests = requests.filter(time => now - time < windowMs)
if (recentRequests.length >= maxRequests) {
return false // 超過速率限制
}
// 新增當前請求
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) // 100 請求/分鐘
if (!allowed) {
return NextResponse.json({
error: 'Rate limit exceeded'
}, { status: 429 })
}
// 繼續處理請求
}
背景任務與佇列
簡單佇列模式
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> {
// 任務執行邏輯
}
}
// 用於索引市場的使用範例
interface IndexJob {
marketId: string
}
const indexQueue = new JobQueue<IndexJob>()
export async function POST(request: Request) {
const { marketId } = await request.json()
// 加入佇列而非阻塞
await indexQueue.add({ marketId })
return NextResponse.json({ success: true, message: 'Job queued' })
}
日誌與監控
結構化日誌
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()
// 使用方式
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 })
}
}
記住：後端模式能實現可擴展、可維護的伺服器端應用程式。選擇符合你複雜度等級的模式。