backend-patterns

name backend-patterns description Node.js, Express ve Next.js API routes için backend mimari kalıpları, API tasarımı, veritabanı optimizasyonu ve sunucu tarafı en iyi uygulamalar. origin ECC Backend Geliştirme Kalıpları Ölçeklenebilir sunucu tarafı uygulamalar için backend mimari kalıpları ve en iyi uygulamalar. Ne Zaman Aktifleştirmelisiniz REST veya GraphQL API endpoint'leri tasarlarken Repository, service veya controller katmanları uygularken Veritabanı sorgularını optimize ederken (N+1, indeksleme, bağlantı havuzu) Önbellekleme eklerken (Redis, in-memory, HTTP cache başlıkları) Arka plan işleri veya async işleme ayarlarken API'ler için hata yönetimi ve doğrulama yapılandırırken Middleware oluştururken (auth, logging, rate limiting) API Tasarım Kalıpları RESTful API Yapısı // PASS: Kaynak tabanlı URL'ler GET /api/markets # Kaynaklar ı listele GET /api/markets/:id # Tek kaynak getir POST /api/markets # Kaynak oluştur PUT /api/markets/:id # Kayna ğı değiş tir (tam) PATCH /api/markets/:id # Kayna ğı gü ncelle (kısmi) DELETE /api/markets/:id # Kayna ğı sil // PASS: Filtreleme, sıralama, sayfalama için query parametreleri GET /api/markets?status=active&sort=volume&limit= 20 &offset= 0 Repository Kalıbı // Veri erişim mantığını soyutla 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 } // Diğer metodlar... } Service Katmanı Kalıbı // İş mantığı veri erişiminden ayrılmış class MarketService { constructor ( private marketRepo : MarketRepository ) {} async searchMarkets ( query : string , limit : number = 10 ): Promise < Market []> { // İş mantığı const embedding = await generateEmbedding (query) const results = await this . vectorSearch (embedding, limit) // Tam veriyi getir const markets = await this . marketRepo . findByIds (results. map ( r => r. id )) // Benzerliğe göre sırala 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 arama implementasyonu } } Middleware Kalıbı // Request/response işleme hattı 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' }) } } } // Kullanım export default withAuth ( async (req, res) => { // Handler req.user'a erişebilir }) Veritabanı Kalıpları Sorgu Optimizasyonu // PASS: İYİ: Sadece gerekli sütunları seç const { data } = await supabase . from ( 'markets' ) . select ( 'id, name, status, volume' ) . eq ( 'status' , 'active' ) . order ( 'volume' , { ascending : false }) . limit ( 10 ) // FAIL: KÖTÜ: Her şeyi seç const { data } = await supabase . from ( 'markets' ) . select ( '*' ) N+1 Sorgu Önleme // FAIL: KÖTÜ: N+1 sorgu problemi const markets = await getMarkets () for ( const market of markets) { market. creator = await getUser (market. creator_id ) // N sorgu } // PASS: İYİ: Toplu getirme const markets = await getMarkets () const creatorIds = markets. map ( m => m. creator_id ) const creators = await getUsers (creatorIds) // 1 sorgu const creatorMap = new Map (creators. map ( c => [c. id , c])) markets. forEach ( market => { market. creator = creatorMap. get (market. creator_id ) }) Transaction Kalıbı async function createMarketWithPosition ( marketData : CreateMarketDto , positionData : CreatePositionDto ) { // Supabase transaction kullan 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'de SQL fonksiyonu CREATE OR REPLACE FUNCTION create_market_with_position ( market_data jsonb, position_data jsonb ) RETURNS jsonb LANGUAGE plpgsql AS $$ BEGIN -- Transaction otomatik başlar INSERT INTO markets VALUES (market_data); INSERT INTO positions VALUES (position_data); RETURN jsonb_build_object ( 'success' , true ); EXCEPTION WHEN OTHERS THEN -- Rollback otomatik olur RETURN jsonb_build_object ( 'success' , false , 'error' , SQLERRM ); END ; $$; Önbellekleme Stratejileri Redis Önbellekleme Katmanı class CachedMarketRepository implements MarketRepository { constructor ( private baseRepo : MarketRepository , private redis : RedisClient ) {} async findById ( id : string ): Promise < Market | null > { // Önce önbelleği kontrol et const cached = await this . redis . get ( `market: ${id} ` ) if (cached) { return JSON . parse (cached) } // Cache miss - veritabanından getir const market = await this . baseRepo . findById (id) if (market) { // 5 dakika önbellekle 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 Kalıbı async function getMarketWithCache ( id : string ): Promise < Market > { const cacheKey = `market: ${id} ` // Önbelleği dene const cached = await redis. get (cacheKey) if (cached) return JSON . parse (cached) // Cache miss - DB'den getir const market = await db. markets . findUnique ({ where : { id } }) if (!market) throw new Error ( 'Market not found' ) // Önbelleği güncelle await redis. setex (cacheKey, 300 , JSON . stringify (market)) return market } Hata Yönetimi Kalıpları Merkezi Hata Yöneticisi 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 }) } // Beklenmeyen hataları logla console . error ( 'Unexpected error:' , error) return NextResponse . json ({ success : false , error : 'Internal server error' }, { status : 500 }) } // Kullanım export async function GET ( request : Request ) { try { const data = await fetchData () return NextResponse . json ({ success : true , data }) } catch (error) { return errorHandler (error, request) } } Exponential Backoff ile Tekrar Deneme 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! } // Kullanım const data = await fetchWithRetry ( () => fetchFromAPI ()) Kimlik Doğrulama ve Yetkilendirme JWT Token Doğrulama 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) } // API route'unda kullanım export async function GET ( request : Request ) { const user = await requireAuth (request) const data = await getDataForUser (user. userId ) return NextResponse . json ({ success : true , data }) } Rol Tabanlı Erişim Kontrolü 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) } } } // Kullanım - HOF handler'ı sarar export const DELETE = requirePermission ( 'delete' )( async ( request : Request , user : User ) => { // Handler doğrulanmış yetki ile kullanıcı alır return new Response ( 'Deleted' , { status : 200 }) } ) Rate Limiting Basit In-Memory Rate Limiter 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) || [] // Pencere dışındaki eski istekleri kaldır const recentRequests = requests. filter ( time => now - time < windowMs) if (recentRequests. length >= maxRequests) { return false // Rate limit aşıldı } // Mevcut isteği ekle 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/dak if (!allowed) { return NextResponse . json ({ error : 'Rate limit exceeded' }, { status : 429 }) } // İstekle devam et } Arka Plan İşleri ve Kuyruklar Basit Kuyruk Kalıbı 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 }