nestjs-best-practices

nestjs-best-practices is a code-quality and architecture reference for NestJS applications, grounded in the official NestJS documentation. It solves the problem of inconsistent structure and anti-patterns in NestJS codebases by codifying enforceable rules across modular architecture, dependency injection scoping, the request lifecycle, error handling, DTO validation, and Drizzle ORM integration, with rationale, do/don't tables, and reusable code templates.

The SKILL.md prescribes strict module encapsulation (one @Module per domain feature, exporting only what other modules need, avoiding forwardRef and the god-module anti-pattern), correct provider scope selection (DEFAULT singletons versus REQUEST and TRANSIENT with constructor injection), and a clear view of the request pipeline (middleware, guards, interceptors, pipes, handler, exception filters). For error handling it recommends extending HttpException, domain-specific exception classes, a global ExceptionFilter, and the Result pattern while never swallowing exceptions. Validation guidance enforces a global ValidationPipe with transform and whitelist, class-validator decorators on all DTO properties, and separate Create/Update/Response DTOs. Database guidance wraps the Drizzle client in an injectable provider, uses the Repository pattern and transactions, and keeps DB logic out of controllers. It ships reference files per topic (module boundaries, DI scoping, exception filters, validation, Drizzle patterns, architecture) and controller/service/module code templates.

It targets TypeScript backend developers designing or refactoring NestJS modules, reviewing code for anti-patterns, or onboarding to an existing NestJS codebase.