Module Reference

Module Reference is a NestJS API that provides dynamic access to providers and modules outside the standard Dependency Injection container, enabling Manual Provider Instantiation.

Usage

Inject ModuleRef to access providers dynamically:

import { ModuleRef } from '@nestjs/core';
 
@Injectable()
export class CatsService {
  constructor(private moduleRef: ModuleRef) {}
 
  async getCircularDependency() {
    // Resolve circular dependency dynamically
    const dogsService = await this.moduleRef.get(DogsService);
    return dogsService.findAll();
  }
 
  async getRequestScopedService() {
    // Must use STRICT scope for request-scoped providers
    const service = await this.moduleRef.resolve(RequestScopedService,
      contextId
    );
  }
}

Key methods

• get(): Retrieve a singleton provider synchronously
• resolve(): Retrieve a provider asynchronously (supports request-scoped)
• create(): Create a new instance of a provider

Use cases

• Breaking circular dependencies
• Dynamic provider selection based on runtime conditions
• Accessing request-scoped providers outside request context
• Testing scenarios requiring manual provider resolution