Essential Nest.js Best Practices for Scalable Backend Development

Nest.js is a modern, enterprise‑grade Node.js web framework. The author shares practical lessons learned from using Nest.js in real projects.

1. Set a global API prefix

Using a global prefix such as /api/v1 helps differentiate API versions and ensures backward compatibility when adding or enhancing endpoints.

2. Organize by modules

Nest.js is built on a modular architecture. Structure your project by feature modules rather than by file type. The recommended layout groups related files (controllers, services, etc.) within a module folder that contains a .module.ts file and an @Module({}) decorator.

3. Use DTOs

Data Transfer Objects (DTOs) define and validate the shape of data for routes and controllers. For example, an AuthDto can enforce that passwords are longer than five characters when combined with class-validator.

4. Prefer Data Mapper/Repository over Active Record

When using relational databases like PostgreSQL or MySQL, choose TypeORM's repository (Data Mapper) pattern instead of Active Record. The repository pattern keeps query logic in separate classes, improving testability and aligning with Nest.js's modular design.

const user = new UserEntity();
user.name = "Vladimir";
user.job = "programmer";
await user.save();

Using a repository:

const user = this.userRepository.create();
user.name = "Vladimir";
user.job = "programmer";
await this.userRepository.save(user);

5. Use relative imports instead of absolute paths

Relative imports (e.g.,

import { SecurityService } from '../security/security.service'

) work reliably during development and build, whereas absolute imports like src/... can cause runtime crashes.

// relative imports
import { SecurityService } from '../security/security.service';
import { CommentService } from '../comment/comment.service';

// absolute imports (not recommended)
import { SecurityService } from 'src/security/security.service';
import { CommentService } from 'src/comment/comment.service';

6. Hide unnecessary fields with @Exclude

Use the @Exclude() decorator from class-transformer to omit sensitive fields (e.g., passwords) when serializing entities.

import { Exclude } from 'class-transformer';

export class UserEntity {
  id: number;
  firstName: string;
  lastName: string;

  @Exclude()
  password: string;

  constructor(partial: Partial<UserEntity>) {
    Object.assign(this, partial);
  }
}

7. Use getter methods in entities

Getter methods can compute derived properties such as a full name, but avoid overloading entities with business logic.

export class UserEntity {
  id: number;
  firstName: string;
  lastName: string;

  get fullName() {
    return this.firstName + " " + this.lastName;
  }
}

8. Export via barrel files

Re‑export DTOs from an index.ts barrel file to simplify imports:

// index.ts
export * from './createPost.dto';
export * from './editPost.dto';
export * from './editPostCategory.dto';
export * from './editPostStatus.dto';

// usage
import { CreatePostDto, EditPostDto } from './dto';