Nestjs Dependency Injection

What it does

This skill enables AI agents to configure and manage dependency injection within NestJS applications, ensuring services are resolved efficiently at runtime. It streamlines the setup of modular architectures by automatically wiring together classes, providers, and tokens without manual instantiation.

When to use it

• Initializing a new NestJS project where automatic service resolution is required.
• Refactoring legacy codebases to adopt a more maintainable, testable architecture using decorators.
• Managing complex application graphs where multiple services depend on shared repositories or utilities.
• Setting up scoped providers for specific modules to isolate state and dependencies.

Key capabilities

• Configures the Module system to register classes as providers.
• Injects dependencies into constructors using standard TypeScript decorators (@Injectable, @Inject).
• Manages singleton and transient scopes for different service lifecycles.
• Resolves circular dependencies through token-based injection patterns.

Example prompts

• "Set up dependency injection for a UserModule that requires a UserRepository and EmailService."
• "Configure a factory provider to dynamically create instances of a specific data source based on an environment variable."
• "Inject a custom token into a controller action to access a scoped service instance."

Tips & gotchas

Ensure you define the @Injectable() decorator on any class intended to be injected, or the framework will throw a resolution error. Be mindful of circular dependencies; if they occur, consider using forward references or token-based injection to break the cycle.