NestJS Dependency Injection

When to Use This Skill

Use this skill when:

• Working with custom providers beyond standard class providers
• Using factory providers for dynamic or async initialization
• Implementing value providers for configuration or constants
• Creating alias providers with useExisting
• Working with non-class-based injection tokens (strings or symbols)
• Implementing async providers that require initialization
• Understanding the three-step provider registration process
• Configuring provider scopes beyond singleton

What is Dependency Injection?

Dependency Injection (DI) is an inversion of control pattern where dependencies are provided to a class rather than the class creating them itself. NestJS has a built-in IoC (Inversion of Control) container that manages the entire DI system.

Three-Step Provider Registration