nestjs-expert
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.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/jeffallan/claude-skills --skill nestjs-expert- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads nestjs-expert automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
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 withnest 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 |
| 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: 'user@example.com' })
@IsEmail()
email: string;
@ApiProperty({ example: '<password>', 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 {}
Unit Test for Service
// users.service.spec.ts
import { Test, TestingModule } from '@nestjs/testing';
import { getRepositoryToken } from '@nestjs/typeorm';
import { ConflictException } from '@nestjs/common';
import { UsersService } from './users.service';
import { User } from './entities/user.entity';
const mockRepo = {
findOneBy: jest.fn(),
create: jest.fn(),
save: jest.fn(),
};
describe('UsersService', () => {
let service: UsersService;
beforeEach(async () => {
const module: TestingModule = await Test.createTestingModule({
providers: [
UsersService,
{ provide: getRepositoryToken(User), useValue: mockRepo },
],
}).compile();
service = module.get<UsersService>(UsersService);
jest.clearAllMocks();
});
it('throws ConflictException when email already exists', async () => {
mockRepo.findOneBy.mockResolvedValue({ id: 1, email: 'user@example.com' });
await expect(
service.create({ email: 'user@example.com', password: '<test-password>' }),
).rejects.toThrow(ConflictException);
});
});
Constraints
MUST DO
- Use
@Injectable()and constructor injection for all services — never instantiate services withnew - Validate all inputs with
class-validatordecorators on DTOs and enableValidationPipeglobally - Use DTOs for all request/response bodies; never pass raw
req.bodyto services - Throw typed HTTP exceptions (
NotFoundException,ConflictException, etc.) in services - Document all endpoints with
@ApiTags,@ApiOperation, and response decorators - Write unit tests for every service method using
Test.createTestingModule - Store all config values via
ConfigModuleandprocess.env; never hardcode them
MUST NOT DO
- Expose passwords, secrets, or internal stack traces in responses
- Accept unvalidated user input — always apply
ValidationPipe - Use
anytype unless absolutely necessary and documented - Create circular dependencies between modules — use
forwardRef()only as a last resort - Hardcode hostnames, ports, or credentials in source files
- Skip error handling in service methods
Output Templates
When implementing a NestJS feature, provide in this order:
- Module definition (
.module.ts) - Controller with Swagger decorators (
.controller.ts) - Service with typed error handling (
.service.ts) - DTOs with
class-validatordecorators (dto/*.dto.ts) - Unit tests for service methods (
*.service.spec.ts)
Knowledge Reference
NestJS, TypeScript, TypeORM, Prisma, Passport, JWT, class-validator, class-transformer, Swagger/OpenAPI, Jest, Supertest, Guards, Interceptors, Pipes, Filters
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions
FAQ
What does the nestjs-expert skill do?
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.
How do I install nestjs-expert?
Run npx skills add https://github.com/jeffallan/claude-skills --skill nestjs-expert in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/nestjs-expert/ (personal) or .claude/skills/nestjs-expert/ (project).
Which AI agents can use nestjs-expert?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is nestjs-expert safe to install?
Security partners have reviewed it: Gen Agent Trust Hub flagged risks; Socket passed; Snyk passed; Runlayer passed; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains nestjs-expert?
It is published by jeffallan in jeffallan/claude-skills. It has 5,944 recorded installs.
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