generic-fullstack-feature-developer

Fullstack Feature Developer

Guide feature development for Next.js/NestJS full-stack applications.

Extends: Generic Feature Developer - Read base skill for development workflow, decision frameworks, data flow patterns, and error handling.

Full-Stack Data Flow

User Action → Event Handler → API Call → NestJS Controller
                                              ↓
UI Update ← Response ← Service ← Prisma ← Database

Request/Response Cycle

// Frontend: Call API
const response = await fetch('/api/users', {
  method: 'POST',
  body: JSON.stringify(userData),
});

// Backend: Handle request
@Post()
@UseGuards(JwtAuthGuard)
async createUser(@Body() dto: CreateUserDto) {
  return this.userService.create(dto);
}

Next.js App Router Patterns

File Conventions

File	Purpose
page.tsx	Route UI (server component by default)
layout.tsx	Shared UI wrapper
loading.tsx	Suspense loading UI
error.tsx	Error boundary
route.ts	API endpoint

Server vs Client Components

// Server Component (default) - can fetch data
export default async function Page() {
  const data = await getData(); // Direct DB/API call
  return <div>{data.title}</div>;
}

// Client Component - needs 'use client'
'use client';
export default function Interactive() {
  const [state, setState] = useState();
  return <button onClick={() => setState(...)}>Click</button>;
}

NestJS Module Pattern

Module → Controller → Service → Prisma

Adding a Feature Module

// 1. Module definition
@Module({
  controllers: [UsersController],
  providers: [UsersService],
  exports: [UsersService],
})
export class UsersModule {}

// 2. Controller with guards
@Controller("users")
@UseGuards(JwtAuthGuard)
export class UsersController {
  @Post()
  create(@Body() dto: CreateUserDto) {
    return this.usersService.create(dto);
  }
}

// 3. Service with Prisma
@Injectable()
export class UsersService {
  constructor(private prisma: PrismaService) {}

  create(dto: CreateUserDto) {
    return this.prisma.user.create({ data: dto });
  }
}