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132 lines
4.8 KiB
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132 lines
4.8 KiB
Markdown
---
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name: nestjs-best-practices
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description: NestJS best practices and architecture patterns for building production-ready applications. This skill should be used when writing, reviewing, or refactoring NestJS code to ensure proper patterns for modules, dependency injection, security, and performance.
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license: MIT
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metadata:
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author: Kadajett
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version: '1.1.0'
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---
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# NestJS Best Practices
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Comprehensive best practices guide for NestJS applications. Contains 40 rules across 10 categories, prioritized by impact to guide automated refactoring and code generation.
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## When to Apply
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Reference these guidelines when:
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- Writing new NestJS modules, controllers, or services
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- Implementing authentication and authorization
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- Reviewing code for architecture and security issues
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- Refactoring existing NestJS codebases
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- Optimizing performance or database queries
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- Building microservices architectures
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## Rule Categories by Priority
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| Priority | Category | Impact | Prefix |
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| -------- | -------------------- | ----------- | ----------- |
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| 1 | Architecture | CRITICAL | `arch-` |
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| 2 | Dependency Injection | CRITICAL | `di-` |
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| 3 | Error Handling | HIGH | `error-` |
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| 4 | Security | HIGH | `security-` |
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| 5 | Performance | HIGH | `perf-` |
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| 6 | Testing | MEDIUM-HIGH | `test-` |
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| 7 | Database & ORM | MEDIUM-HIGH | `db-` |
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| 8 | API Design | MEDIUM | `api-` |
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| 9 | Microservices | MEDIUM | `micro-` |
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| 10 | DevOps & Deployment | LOW-MEDIUM | `devops-` |
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## Quick Reference
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### 1. Architecture (CRITICAL)
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- `arch-avoid-circular-deps` - Avoid circular module dependencies
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- `arch-feature-modules` - Organize by feature, not technical layer
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- `arch-module-sharing` - Proper module exports/imports, avoid duplicate providers
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- `arch-single-responsibility` - Focused services over "god services"
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- `arch-use-repository-pattern` - Abstract database logic for testability
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- `arch-use-events` - Event-driven architecture for decoupling
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### 2. Dependency Injection (CRITICAL)
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- `di-avoid-service-locator` - Avoid service locator anti-pattern
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- `di-interface-segregation` - Interface Segregation Principle (ISP)
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- `di-liskov-substitution` - Liskov Substitution Principle (LSP)
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- `di-prefer-constructor-injection` - Constructor over property injection
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- `di-scope-awareness` - Understand singleton/request/transient scopes
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- `di-use-interfaces-tokens` - Use injection tokens for interfaces
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### 3. Error Handling (HIGH)
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- `error-use-exception-filters` - Centralized exception handling
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- `error-throw-http-exceptions` - Use NestJS HTTP exceptions
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- `error-handle-async-errors` - Handle async errors properly
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### 4. Security (HIGH)
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- `security-auth-jwt` - Secure JWT authentication
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- `security-validate-all-input` - Validate with class-validator
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- `security-use-guards` - Authentication and authorization guards
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- `security-sanitize-output` - Prevent XSS attacks
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- `security-rate-limiting` - Implement rate limiting
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### 5. Performance (HIGH)
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- `perf-async-hooks` - Proper async lifecycle hooks
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- `perf-use-caching` - Implement caching strategies
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- `perf-optimize-database` - Optimize database queries
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- `perf-lazy-loading` - Lazy load modules for faster startup
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### 6. Testing (MEDIUM-HIGH)
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- `test-use-testing-module` - Use NestJS testing utilities
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- `test-e2e-supertest` - E2E testing with Supertest
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- `test-mock-external-services` - Mock external dependencies
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### 7. Database & ORM (MEDIUM-HIGH)
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- `db-use-transactions` - Transaction management
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- `db-avoid-n-plus-one` - Avoid N+1 query problems
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- `db-use-migrations` - Use migrations for schema changes
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### 8. API Design (MEDIUM)
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- `api-use-dto-serialization` - DTO and response serialization
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- `api-use-interceptors` - Cross-cutting concerns
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- `api-versioning` - API versioning strategies
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- `api-use-pipes` - Input transformation with pipes
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### 9. Microservices (MEDIUM)
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- `micro-use-patterns` - Message and event patterns
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- `micro-use-health-checks` - Health checks for orchestration
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- `micro-use-queues` - Background job processing
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### 10. DevOps & Deployment (LOW-MEDIUM)
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- `devops-use-config-module` - Environment configuration
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- `devops-use-logging` - Structured logging
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- `devops-graceful-shutdown` - Zero-downtime deployments
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## How to Use
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Read individual rule files for detailed explanations and code examples:
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```
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rules/arch-avoid-circular-deps.md
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rules/security-validate-all-input.md
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rules/_sections.md
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```
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Each rule file contains:
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- Brief explanation of why it matters
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- Incorrect code example with explanation
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- Correct code example with explanation
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- Additional context and references
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## Full Compiled Document
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For the complete guide with all rules expanded: `AGENTS.md`
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