backend-rules

Backend Development Rules

Tech Stack

• Node.js 20+
• TypeScript 5+
• Express / Fastify
• Prisma ORM
• PostgreSQL / MySQL

---

Project Structure

server/
├── src/
│   ├── routes/        # Route definitions
│   ├── controllers/   # Controllers
│   ├── services/      # Business logic
│   ├── models/        # Data models
│   ├── middleware/    # Middleware
│   ├── utils/         # Utility functions
│   ├── types/         # Type definitions
│   ├── config/        # Configuration files
│   └── app.ts         # Application entry
├── prisma/
│   └── schema.prisma  # Database models
└── tests/
    ├── unit/
    └── integration/

---

API Design Standards

RESTful API

GET    /api/users           # Get user list
GET    /api/users/:id       # Get single user
POST   /api/users           # Create user
PUT    /api/users/:id       # Update user
DELETE /api/users/:id       # Delete user

Response Format

// Success response
interface SuccessResponse<T> {
  success: true;
  data: T;
  message?: string;
}

// Error response
interface ErrorResponse {
  success: false;
  error: {
    code: string;
    message: string;
    details?: unknown;
  };
}

// Paginated response
interface PaginatedResponse<T> {
  success: true;
  data: T[];
  pagination: {
    page: number;
    limit: number;
    total: number;
    totalPages: number;
  };
}

Status Code Standards

200 OK              # Success
201 Created         # Created successfully
204 No Content      # Deleted successfully
400 Bad Request     # Invalid request parameters
401 Unauthorized    # Not authenticated
403 Forbidden       # No permission
404 Not Found       # Resource not found
409 Conflict        # Resource conflict
422 Unprocessable   # Validation failed
500 Internal Error  # Server error

---

Controller Standards

Controller Template

import { Request, Response, NextFunction } from 'express';
import { UserService } from '../services/user.service';
import { AppError } from '../middleware/error';

export class UserController {
  constructor(private userService: UserService) {}

  async getUsers(req: Request, res: Response, next: NextFunction) {
    try {
      const { page = 1, limit = 10 } = req.query;
      const result = await this.userService.findAll({
        page: Number(page),
        limit: Number(limit)
      });
      
      res.json({
        success: true,
        data: result.data,
        pagination: result.pagination
      });
    } catch (error) {
      next(error);
    }
  }

  async createUser(req: Request, res: Response, next: NextFunction) {
    try {
      const user = await this.userService.create(req.body);
      
      res.status(201).json({
        success: true,
        data: user,
        message: 'User created successfully'
      });
    } catch (error) {
      next(error);
    }
  }
}