nestjs

SKILL.md

NestJS Framework with Drizzle ORM

Overview

Provides NestJS patterns with Drizzle ORM for building production-ready server-side applications. Covers CRUD modules, JWT authentication, database operations, migrations, testing, microservices, and GraphQL integration.

When to Use

Building REST APIs or GraphQL servers with NestJS

Setting up authentication and authorization with JWT

Implementing database operations with Drizzle ORM

Creating microservices with TCP/Redis transport

Writing unit and integration tests

Running database migrations with drizzle-kit

Instructions

Install dependencies: npm i drizzle-orm pg && npm i -D drizzle-kit tsx

Define schema: Create src/db/schema.ts with Drizzle table definitions

Create DatabaseService: Inject Drizzle client as a NestJS provider

Build CRUD module: Controller → Service → Repository pattern

Add validation: Use class-validator DTOs with ValidationPipe

Implement guards: Create JWT/Roles guards for route protection

Write tests: Use @nestjs/testing with mocked repositories

Run migrations: npx drizzle-kit generate → Verify SQL → npx drizzle-kit migrate

Examples

Complete CRUD Module with Drizzle

// src/db/schema.ts
export const users = pgTable('users', {
  id: serial('id').primaryKey(),
  name: text('name').notNull(),
  email: text('email').notNull().unique(),
  createdAt: timestamp('created_at').defaultNow(),
});

// src/users/dto/create-user.dto.ts
export class CreateUserDto {
  @IsString() @IsNotEmpty() name: string;
  @IsEmail() email: string;
}

// src/users/user.repository.ts
@Injectable()
export class UserRepository {
  constructor(private db: DatabaseService) {}

  async findAll() {
    return this.db.database.select().from(users);
  }

  async create(data: typeof users.$inferInsert) {
    return this.db.database.insert(users).values(data).returning();
  }
}

// src/users/users.service.ts
@Injectable()
export class UsersService {
  constructor(private repo: UserRepository) {}

  async create(dto: CreateUserDto) {
    return this.repo.create(dto);
  }
}

// src/users/users.controller.ts
@Controller('users')
export class UsersController {
  constructor(private service: UsersService) {}

  @Post()
  create(@Body() dto: CreateUserDto) {
    return this.service.create(dto);
  }
}

// src/users/users.module.ts
@Module({
  controllers: [UsersController],
  providers: [UsersService, UserRepository, DatabaseService],
  exports: [UsersService],
})
export class UsersModule {}

JWT Authentication Guard

@Injectable()
export class JwtAuthGuard implements CanActivate {
  constructor(private jwtService: JwtService) {}

  canActivate(context: ExecutionContext) {
    const token = context.switchToHttp().getRequest()
      .headers.authorization?.split(' ')[1];
    if (!token) return false;
    try {
      const decoded = this.jwtService.verify(token);
      context.switchToHttp().getRequest().user = decoded;
      return true;
    } catch {
      return false;
    }
  }
}

Database Transactions

async transferFunds(fromId: number, toId: number, amount: number) {
  return this.db.database.transaction(async (tx) => {
    await tx.update(accounts)
      .set({ balance: sql`${accounts.balance} - ${amount}` })
      .where(eq(accounts.id, fromId));
    await tx.update(accounts)
      .set({ balance: sql`${accounts.balance} + ${amount}` })
      .where(eq(accounts.id, toId));
  });
}

Unit Testing with Mocks

describe('UsersService', () => {
  let service: UsersService;
  let repo: jest.Mocked<UserRepository>;

  beforeEach(async () => {
    const module = await Test.createTestingModule({
      providers: [
        UsersService,
        { provide: UserRepository, useValue: { findAll: jest.fn(), create: jest.fn() } },
      ],
    }).compile();
    service = module.get(UsersService);
    repo = module.get(UserRepository);
  });

  it('should create user', async () => {
    const dto = { name: 'John', email: 'john@example.com' };
    repo.create.mockResolvedValue({ id: 1, ...dto, createdAt: new Date() });
    expect(await service.create(dto)).toMatchObject(dto);
  });
});

Constraints and Warnings

DTOs required: Always use DTOs with class-validator, never accept raw objects

Transactions: Keep transactions short; avoid nested transactions

Guards order: JWT guard must run before Roles guard

Environment variables: Never hardcode DATABASE_URL or JWT_SECRET

Migrations: Run drizzle-kit generate after schema changes before deploying

Circular dependencies: Use forwardRef() carefully; prefer module restructuring

Best Practices

Validate all inputs with global ValidationPipe

Use transactions for multi-table operations

Document APIs with OpenAPI/Swagger decorators

References

Advanced patterns and detailed examples available in:

references/reference.md - Core patterns, guards, interceptors, microservices, GraphQL

references/drizzle-reference.md - Drizzle ORM installation, configuration, queries

references/workflow-optimization.md - Development workflows, parallel execution strategies