alinaqi/maggy

nodejs-backend

Node.js backend patterns with Express/Fastify, repositories

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사용 방법

  1. 설치 명령을 복사하고 자신의 에이전트 환경에 설치하기 전에 소스 패키지를 확인하세요.
  2. 필요한 도구, 인증 정보, 지원 환경은 원본 문서에서 확인하세요.
  3. 입력과 원하는 산출물을 설명하고 출처와 결과를 대조하세요.
npx skills add https://github.com/alinaqi/maggy --skill nodejs-backend

시작 전 확인

  • 설치에는 모델 구독, API 한도, 파일 접근 권한이 포함되지 않습니다.
  • 별점 수와 설치 수는 활동 지표이며 독립적인 품질·보안 검증이 아닙니다.
원본 Skill 문서

원본 저장소의 제목, 예시, 코드, 표, 링크, 이미지를 유지해 표시합니다.

Node.js Backend Skill


Project Structure

project/
├── src/
│   ├── core/                   # Pure business logic
│   │   ├── types.ts            # Domain types
│   │   ├── errors.ts           # Domain errors
│   │   └── services/           # Pure functions
│   │       ├── user.ts
│   │       └── order.ts
│   ├── infra/                  # Side effects
│   │   ├── http/               # HTTP layer
│   │   │   ├── server.ts       # Server setup
│   │   │   ├── routes/         # Route handlers
│   │   │   └── middleware/     # Express middleware
│   │   ├── db/                 # Database
│   │   │   ├── client.ts       # DB connection
│   │   │   ├── repositories/   # Data access
│   │   │   └── migrations/     # Schema migrations
│   │   └── external/           # Third-party APIs
│   ├── config/                 # Configuration
│   │   └── index.ts            # Env vars, validated
│   └── index.ts                # Entry point
├── tests/
│   ├── unit/
│   └── integration/
├── package.json
└── CLAUDE.md

API Design

Route Handler Pattern

typescript
// routes/users.ts
import { Router } from 'express';
import { z } from 'zod';
import { createUser } from '../../core/services/user';
import { UserRepository } from '../db/repositories/user';

const CreateUserSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1).max(100),
});

export function createUserRoutes(userRepo: UserRepository): Router {
  const router = Router();

  router.post('/', async (req, res, next) => {
    try {
      const input = CreateUserSchema.parse(req.body);
      const user = await createUser(input, userRepo);
      res.status(201).json(user);
    } catch (error) {
      next(error);
    }
  });

  return router;
}

Dependency Injection at Composition Root

typescript
// index.ts
import { createApp } from './infra/http/server';
import { createDbClient } from './infra/db/client';
import { UserRepository } from './infra/db/repositories/user';
import { createUserRoutes } from './infra/http/routes/users';

async function main(): Promise<void> {
  const db = await createDbClient();
  const userRepo = new UserRepository(db);
  
  const app = createApp({
    userRoutes: createUserRoutes(userRepo),
  });
  
  app.listen(3000);
}

Error Handling

Domain Errors

typescript
// core/errors.ts
export class DomainError extends Error {
  constructor(
    message: string,
    public readonly code: string,
    public readonly statusCode: number = 400
  ) {
    super(message);
    this.name = 'DomainError';
  }
}

export class NotFoundError extends DomainError {
  constructor(resource: string, id: string) {
    super(`${resource} with id ${id} not found`, 'NOT_FOUND', 404);
  }
}

export class ValidationError extends DomainError {
  constructor(message: string) {
    super(message, 'VALIDATION_ERROR', 400);
  }
}

Global Error Handler

typescript
// middleware/errorHandler.ts
import { ErrorRequestHandler } from 'express';
import { DomainError } from '../../core/errors';
import { ZodError } from 'zod';

export const errorHandler: ErrorRequestHandler = (err, req, res, next) => {
  if (err instanceof DomainError) {
    return res.status(err.statusCode).json({
      error: { code: err.code, message: err.message },
    });
  }

  if (err instanceof ZodError) {
    return res.status(400).json({
      error: { code: 'VALIDATION_ERROR', details: err.errors },
    });
  }

  console.error('Unexpected error:', err);
  return res.status(500).json({
    error: { code: 'INTERNAL_ERROR', message: 'Something went wrong' },
  });
};

Database Patterns

Repository Pattern

typescript
// db/repositories/user.ts
import { Kysely } from 'kysely';
import { Database, User } from '../types';

export class UserRepository {
  constructor(private db: Kysely<Database>) {}

  async findById(id: string): Promise<User | null> {
    return this.db
      .selectFrom('users')
      .where('id', '=', id)
      .selectAll()
      .executeTakeFirst() ?? null;
  }

  async create(data: Omit<User, 'id' | 'createdAt'>): Promise<User> {
    return this.db
      .insertInto('users')
      .values(data)
      .returningAll()
      .executeTakeFirstOrThrow();
  }
}

Transactions

typescript
async function transferFunds(
  fromId: string,
  toId: string,
  amount: number,
  db: Kysely<Database>
): Promise<void> {
  await db.transaction().execute(async (trx) => {
    await trx
      .updateTable('accounts')
      .set((eb) => ({ balance: eb('balance', '-', amount) }))
      .where('id', '=', fromId)
      .execute();

    await trx
      .updateTable('accounts')
      .set((eb) => ({ balance: eb('balance', '+', amount) }))
      .where('id', '=', toId)
      .execute();
  });
}

Configuration

Validated Config

typescript
// config/index.ts
import { z } from 'zod';

const ConfigSchema = z.object({
  NODE_ENV: z.enum(['development', 'production', 'test']),
  PORT: z.coerce.number().default(3000),
  DATABASE_URL: z.string().url(),
  API_KEY: z.string().min(1),
});

export type Config = z.infer<typeof ConfigSchema>;

export function loadConfig(): Config {
  return ConfigSchema.parse(process.env);
}

Testing

Unit Tests (Core)

typescript
// tests/unit/services/user.test.ts
import { createUser } from '../../../src/core/services/user';

describe('createUser', () => {
  it('creates user with valid data', async () => {
    const mockRepo = {
      create: jest.fn().mockResolvedValue({ id: '1', email: 'test@example.com' }),
      findByEmail: jest.fn().mockResolvedValue(null),
    };

    const result = await createUser({ email: 'test@example.com', name: 'Test' }, mockRepo);

    expect(result.email).toBe('test@example.com');
    expect(mockRepo.create).toHaveBeenCalledTimes(1);
  });
});

Integration Tests (API)

typescript
// tests/integration/users.test.ts
import request from 'supertest';
import { createTestApp, createTestDb } from '../helpers';

describe('POST /users', () => {
  let app: Express;
  let db: TestDb;

  beforeAll(async () => {
    db = await createTestDb();
    app = createTestApp(db);
  });

  afterAll(async () => {
    await db.destroy();
  });

  it('creates user and returns 201', async () => {
    const response = await request(app)
      .post('/users')
      .send({ email: 'new@example.com', name: 'New User' });

    expect(response.status).toBe(201);
    expect(response.body.email).toBe('new@example.com');
  });
});

Node.js Anti-Patterns

  • ❌ Callback hell - use async/await
  • ❌ Unhandled promise rejections - always catch or let error handler catch
  • ❌ Blocking the event loop - offload heavy computation
  • ❌ Secrets in code - use environment variables
  • ❌ SQL string concatenation - use parameterized queries
  • ❌ No input validation - validate at API boundary
  • ❌ Console.log in production - use proper logger
  • ❌ No graceful shutdown - handle SIGTERM
  • ❌ Monolithic route files - split by resource

관련 작업

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