NestJS Development Skill

Quick Reference

# Scaffold a new module with CRUD
python scripts/scaffold.py user --crud

# Generate specific component
python scripts/generate.py controller user
python scripts/generate.py service user --repository

# Run tests with coverage
python scripts/test.py --coverage --threshold 80

Load Additional Resources

Scenario	Reference	Description
Architecture decisions	references/architecture.md	Clean arch, DDD, CQRS
Auth/Authorization	references/security.md	JWT, Passport, RBAC
Database integration	references/database.md	TypeORM, Prisma
Testing strategies	references/testing.md	Unit, E2E, mocking
Performance	references/performance.md	Caching, queues

Core Patterns

Module Structure

// REQ-XXX: Feature module
@Module({
  imports: [TypeOrmModule.forFeature([User]), ConfigModule],
  controllers: [UserController],
  providers: [UserService, UserRepository],
  exports: [UserService],
})
export class UserModule {}

Service Pattern

@Injectable()
export class UserService {
  constructor(
    private readonly userRepository: UserRepository,
    private readonly eventEmitter: EventEmitter2,
  ) {}

  async create(dto: CreateUserDto): Promise<User> {
    const user = await this.userRepository.create(dto);
    this.eventEmitter.emit('user.created', user);
    return user;
  }
}

Controller Pattern

@ApiTags('users')
@Controller('users')
@UseGuards(JwtAuthGuard, RolesGuard)
export class UserController {
  constructor(private readonly userService: UserService) {}

  @Post()
  @Roles(Role.ADMIN)
  @ApiOperation({ summary: 'Create user' })
  @ApiResponse({ status: 201, type: UserResponseDto })
  async create(@Body() dto: CreateUserDto): Promise<UserResponseDto> {
    return this.userService.create(dto);
  }
}

DTO with Validation

export class CreateUserDto {
  @ApiProperty({ example: 'john@example.com' })
  @IsEmail()
  @IsNotEmpty()
  email: string;

  @ApiProperty({ minLength: 8 })
  @IsString()
  @MinLength(8)
  @Matches(/^(?=.*[A-Za-z])(?=.*\d)/)
  password: string;
}

Guard Pattern

@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private reflector: Reflector) {}

  canActivate(context: ExecutionContext): boolean {
    const requiredRoles = this.reflector.getAllAndOverride<Role[]>(
      ROLES_KEY, [context.getHandler(), context.getClass()],
    );
    if (!requiredRoles) return true;
    const { user } = context.switchToHttp().getRequest();
    return requiredRoles.some((role) => user.roles?.includes(role));
  }
}

Project Structure

src/
├── main.ts                    # Bootstrap
├── app.module.ts              # Root module
├── common/                    # Shared utilities
│   ├── decorators/           # @Roles, @User, @Public
│   ├── dto/                  # PaginationDto, ResponseDto
│   ├── filters/              # HttpExceptionFilter
│   ├── guards/               # JwtAuthGuard, RolesGuard
│   ├── interceptors/         # TransformInterceptor
│   └── pipes/                # ValidationPipe extensions
├── config/                    # Configuration
└── modules/                   # Feature modules
    └── {feature}/
        ├── {feature}.module.ts
        ├── {feature}.controller.ts
        ├── {feature}.service.ts
        ├── {feature}.repository.ts
        ├── dto/
        ├── entities/
        └── __tests__/

F5 Quality Gates

Gate	Requirement	Implementation
D3	Architecture	Module structure documented
D4	Detailed Design	DTOs, entities defined
G2.5	Code Review	NestJS best practices
G3	80% Coverage	Jest + supertest

Scripts

Script	Usage	Gate
scaffold.py	scaffold.py <name> --crud	D4
generate.py	generate.py <type> <name>	G2.5
test.py	test.py --coverage	G3

Common Packages

{
  "@nestjs/core": "^10.0.0",
  "@nestjs/common": "^10.0.0",
  "@nestjs/config": "^3.0.0",
  "@nestjs/typeorm": "^10.0.0",
  "@nestjs/passport": "^10.0.0",
  "@nestjs/jwt": "^10.0.0",
  "@nestjs/swagger": "^7.0.0",
  "class-validator": "^0.14.0"
}