NestJSAdvanced

NestJS Best Practices

Structure, DTO everywhere, error handling, performance, security — সেরা অভ্যাস বাংলায়।

15টি অংশবাংলা ভাষায়

1. Proper Folder Structure

src/
├── modules/            # feature modules
│   ├── users/
│   │   ├── users.module.ts
│   │   ├── users.controller.ts
│   │   ├── users.service.ts
│   │   ├── dto/
│   │   ├── schemas/  (বা entities/)
│   │   └── test files
│   └── auth/
├── common/            # shared
│   ├── guards/
│   ├── pipes/
│   ├── interceptors/
│   ├── decorators/
│   └── filters/
├── types/             # shared interfaces
├── config/
└── main.ts

2. DTO সর্বত্র

// ❌ avoid — any
create(@Body() body: any) {}

// ✅ DTO
@Post()
create(@Body() dto: CreateUserDto) {}

// separate dto per operation
// CreateUserDto, UpdateUserDto, LoginDto

3. Single Responsibility

// Controller → HTTP layer শুধু
// Service → business logic
// Repository/Model → data access
// Module → grouping

// ❌ controller-এ DB logic
@Get()
async findAll(@Query() q: any) {
  const db = await getDb();
  return db.collection('users').find().toArray();
}

// ✅ service-এ
@Get()
findAll() {
  return this.usersService.findAll();
}

4. Global Validation & Filters

main.ts — production baselinetypescript

typescript

import { ValidationPipe, Logger } from "@nestjs/common";
import { HttpAdapterHost, NestFactory } from "@nestjs/core";

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  app.setGlobalPrefix("api/v1"); // versioning

  app.useGlobalPipes(new ValidationPipe({ whitelist: true, transform: true }));

  app.enableCors({ origin: process.env.FRONTEND_URL });

  app.useLogger(["error", "warn", "log"]);

  await app.listen(3000);
}
bootstrap();

5. Performance

# build production
npm run build

# run — NODE_ENV=production + cluster
pm2 start dist/main.js -i max

# enable gzip (nginx বা compression)
# app.use(compression()) — अगर application server

6. Security Checklist

// main.ts
import { NestFactory } from "@nestjs/core";
import { helmet } from "helmet";

// helmet
app.use(helmet());

// rate limit (nestjs-rate-limiter package)
app.enableCors({
  origin: ["https://myapp.com"],
  credentials: true,
});

# extra packages
npm i helmet express-rate-limit

✔	অভ্যাস
✔	DTO + class-validator (whitelist)
✔	Guards দিয়ে authorization
✔	Swagger docs (api tags)
✔	Global exception format
✔	ConfigModule + env validation
✔	Unit + e2e test
✔	Controller thin, Service logic
✔	Helmet + rate limit + CORS
✔	Versioned prefix /api/v1
✔	Logging (nestjs Logger/class-validator)

Opensource reference

NestJS-এর অফিসিয়াল nestjs/sample repositories প্রতিটি concept-এর reference — শুরুতে ওগুলো পড়ে অনুসরণ করা ভালো।

শেষ প্যারায় নিজে practice করুন — কোড কপি করে নিজের এডিটরে চালিয়ে দেখুন।