Creates and configures NestJS modules, controllers, services, DTOs, guards, and interceptors for enterprise-grade TypeScript backend applications. Use when building NestJS REST APIs or GraphQL services, implementing dependency injection, scaffolding modular architecture, adding JWT/Passport authentication, integrating TypeORM or Prisma, or working with .module.ts, .controller.ts, and .service.ts files. Invoke for guards, interceptors, pipes, validation, Swagger documentation, and unit/E2E testing in NestJS projects.
SKILL.md
NestJS Expert
Senior NestJS specialist with deep expertise in enterprise-grade, scalable TypeScript backend applications.
Core Workflow
Analyze requirements — Identify modules, endpoints, entities, and relationships
Design structure — Plan module organization and inter-module dependencies
Implement — Create modules, services, and controllers with proper DI wiring
Secure — Add guards, validation pipes, and authentication
Verify — Run npm run lint, npm run test, and confirm DI graph with nest info
Test — Write unit tests for services and E2E tests for controllers
Reference Guide
Load detailed guidance based on context:
Topic
Reference
Load When
Controllers
references/controllers-routing.md
Creating controllers, routing, Swagger docs
Services
references/services-di.md
Services, dependency injection, providers
DTOs
references/dtos-validation.md
Validation, class-validator, DTOs
Authentication
references/authentication.md
JWT, Passport, guards, authorization
0
Testing
references/testing-patterns.md
Unit tests, E2E tests, mocking
Express Migration
references/migration-from-express.md
Migrating from Express.js to NestJS
Code Examples
Controller with DTO Validation and Swagger
// create-user.dto.ts
import { IsEmail, IsString, MinLength } from 'class-validator';
import { ApiProperty } from '@nestjs/swagger';
export class CreateUserDto {
@ApiProperty({ example: '[email protected]' })
@IsEmail()
email: string;
@ApiProperty({ example: 'strongPassword123', minLength: 8 })
@IsString()
@MinLength(8)
password: string;
}
// users.controller.ts
import { Body, Controller, Post, HttpCode, HttpStatus } from '@nestjs/common';
import { ApiCreatedResponse, ApiTags } from '@nestjs/swagger';
import { UsersService } from './users.service';
import { CreateUserDto } from './dto/create-user.dto';
@ApiTags('users')
@Controller('users')
export class UsersController {
constructor(private readonly usersService: UsersService) {}
@Post()
@HttpCode(HttpStatus.CREATED)
@ApiCreatedResponse({ description: 'User created successfully.' })
create(@Body() createUserDto: CreateUserDto) {
return this.usersService.create(createUserDto);
}
}
Service with Dependency Injection and Error Handling
// users.service.ts
import { Injectable, ConflictException, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { User } from './entities/user.entity';
import { CreateUserDto } from './dto/create-user.dto';
@Injectable()
export class UsersService {
constructor(
@InjectRepository(User)
private readonly usersRepository: Repository<User>,
) {}
async create(createUserDto: CreateUserDto): Promise<User> {
const existing = await this.usersRepository.findOneBy({ email: createUserDto.email });
if (existing) {
throw new ConflictException('Email already registered');
}
const user = this.usersRepository.create(createUserDto);
return this.usersRepository.save(user);
}
async findOne(id: number): Promise<User> {
const user = await this.usersRepository.findOneBy({ id });
if (!user) {
throw new NotFoundException(`User #${id} not found`);
}
return user;
}
}
Module Definition
// users.module.ts
import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';
import { User } from './entities/user.entity';
@Module({
imports: [TypeOrmModule.forFeature([User])],
controllers: [UsersController],
providers: [UsersService],
exports: [UsersService], // export only when other modules need this service
})
export class UsersModule {}
