backend-patterns

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
})