nestjs-api

API Rules (NestJS)

Template for NestJS backend projects.

Module Structure

src/
├── modules/
│   ├── auth/
│   │   ├── auth.controller.ts
│   │   ├── auth.service.ts
│   │   ├── auth.module.ts
│   │   └── dto/
│   └── users/
│       ├── users.controller.ts
│       ├── users.service.ts
│       ├── users.module.ts
│       ├── entities/
│       └── dto/
├── common/
│   ├── decorators/
│   ├── guards/
│   ├── interceptors/
│   └── pipes/
└── config/

Patterns

Controllers

@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Get()
  findAll(): Promise<User[]> {
    return this.usersService.findAll();
  }

  @Post()
  @UsePipes(ValidationPipe)
  create(@Body() dto: CreateUserDto): Promise<User> {
    return this.usersService.create(dto);
  }
}

DTOs with Validation

import { IsEmail, IsString, MinLength } from 'class-validator';

export class CreateUserDto {
  @IsEmail()
  email: string;

  @IsString()
  @MinLength(8)
  password: string;
}

Services

@Injectable()
export class UsersService {
  constructor(
    @InjectRepository(User)
    private readonly userRepository: Repository<User>,
  ) {}

  async findAll(): Promise<User[]> {
    return this.userRepository.find();
  }
}

Database

• TypeORM for PostgreSQL/MySQL
• Prisma as alternative
• Migrations in src/database/migrations/

Error Handling

// Use built-in HTTP exceptions
throw new NotFoundException('User not found');
throw new BadRequestException('Invalid input');
throw new UnauthorizedException('Not authenticated');

Testing

npm run test        # Unit tests
npm run test:e2e    # E2E tests

Commands

npm run start:dev   # Development
npm run build       # Production build
npm run migration:run  # Run migrations