backend-coding

Backend Coding

Build production-ready backend services with proper architecture, security, performance optimization, and testing.

Core Development Workflow

Follow this systematic approach for backend implementation:

1. Design API Endpoints

Define clear, RESTful API contracts before implementation.

REST API Design Pattern:

Resource-based URLs (use plural nouns):
✅ GET    /api/v1/users              - List users (paginated)
✅ GET    /api/v1/users/:id          - Get user by ID
✅ POST   /api/v1/users              - Create new user
✅ PUT    /api/v1/users/:id          - Replace entire user
✅ PATCH  /api/v1/users/:id          - Update user fields
✅ DELETE /api/v1/users/:id          - Delete user

❌ Avoid verb-based URLs:
❌ /api/v1/getUsers
❌ /api/v1/createUser

Basic Example (Express.js):

router.get('/users',
  query('page').optional().isInt({ min: 1 }).toInt(),
  query('limit').optional().isInt({ min: 1, max: 100 }).toInt(),
  async (req, res, next) => {
    try {
      const errors = validationResult(req);
      if (!errors.isEmpty()) {
        return res.status(400).json({ errors: errors.array() });
      }

      const page = req.query.page as number || 1;
      const limit = req.query.limit as number || 20;
      const offset = (page - 1) * limit;

      const { users, total } = await userService.findAll({ 
        limit, offset 
      });

      res.json({
        data: users,
        pagination: { page, limit, total }
      });
    } catch (error) {
      next(error);
    }
  }
);

For complete patterns: api-design.md

2. Implement Database Layer

Use repository pattern for clean separation and testability.

Repository Pattern (TypeORM):

export class UserRepository {
  private repository: Repository<User>;

  async findAll(params: { search?: string; limit: number; offset: number }) {
    const queryBuilder = this.repository
      .createQueryBuilder('user')
      .orderBy('user.createdAt', 'DESC');

    if (params.search) {
      queryBuilder.where(
        'user.name ILIKE :search OR user.email ILIKE :search',
        { search: `%${params.search}%` }
      );
    }

    return queryBuilder
      .take(params.limit)
      .skip(params.offset)
      .getManyAndCount();
  }

  async create(userData: UserCreate): Promise<User> {
    const hashedPassword = await bcrypt.hash(userData.password, 12);
    const user = this.repository.create({
      ...userData,
      password: hashedPassword
    });
    return this.repository.save(user);
  }
}