Heldinhow NestJS API Development
Overview
NestJS is a progressive Node.js framework for building scalable, enterprise-grade applications using TypeScript. This skill should be invoked when creating enterprise Node.js APIs, microservices, or backend applications that require strong architecture, dependency injection, and modular organization.
Core Principles
- Modular Architecture: Organize code into modules that encapsulate related functionality
- Dependency Injection: Leverage NestJS's built-in DI container for loose coupling
- Decorator-Based: Use decorators for routing, validation, and authentication
- TypeScript First: Benefit from full TypeScript support with static typing
Preparation Checklist
- Initialize NestJS project:
nest new project-name - Plan module structure (users, products, orders, etc.)
- Choose database integration (TypeORM, Prisma, Mongoose)
- Decide on validation approach (class-validator, built-in pipes)
Step-by-Step Process
- Initialize: Create new NestJS project
- Generate Modules: Use CLI to create modules:
nest g module users - Create Components: Generate controllers and services
- Configure DI: Set up providers and injections
- Add Validation: Implement validation pipes for request bodies
- Integrate Database: Connect TypeORM/Prisma for data persistence
Do's and Don'ts
- ✅ Do use the CLI for generating components to maintain convention
- ✅ Do keep business logic in services, not controllers
- ✅ Do use guards for authorization and interceptors for logging
- ❌ Don't put all logic in one module - loses architectural benefits
- ❌ Don't skip validation - always validate incoming data
- ❌ Don't ignore exception filters for consistent error handling
Anti-Patterns
- The Monolith Module: Putting everything in a single module
- Logic in Controllers: Adding business logic directly in controller methods
- Missing Error Handling: Not implementing global exception filters
- No Validation: Accepting user input without validation pipes