LazyModuleLoader

Kind: Class

Source: packages/core/injector/lazy-module-loader/lazy-module-loader.ts

Part of: Core

LazyModuleLoader loads Nest modules on demand instead of during application bootstrap. It creates and registers a module dynamically, returning a ModuleRef that can be used to resolve providers from the loaded module.

Methods

Diagram

mermaid
graph LR
  A[Application Service] --> B[LazyModuleLoader]
  B --> C[load module factory]
  C --> D[Dynamic Module Import]
  D --> E[ModuleRef]
  E --> F[Resolve Module Providers]

Usage

ts
import { Injectable } from '@nestjs/common';
import { LazyModuleLoader } from '@nestjs/core';
import { ReportsService } from './reports.service';

@Injectable()
export class DashboardService {
  constructor(private readonly lazyModuleLoader: LazyModuleLoader) {}

  async loadReports() {
    const moduleRef = await this.lazyModuleLoader.load(() =>
      import('./reports/reports.module').then(({ ReportsModule }) => ReportsModule),
    );

    const reportsService = moduleRef.get(ReportsService);
    return reportsService.getSummary();
  }
}

AI Coding Instructions

• Inject LazyModuleLoader from @nestjs/core into a provider; do not instantiate it manually.
• Pass a loader callback to load() so the module is imported only when it is needed.
• Return the module class or dynamic module definition from the loader callback, typically using import(...).then(...).
• Use the returned ModuleRef to retrieve providers registered by the lazy-loaded module.
• Ensure providers needed from the loaded module are declared or exported correctly within that module.

How it works

LazyModuleLoader is a class that asynchronously loads a module class or dynamic-module definition into the Nest module container and returns that module’s ModuleRef. Its constructor receives a DependenciesScanner, InstanceLoader, ModuleCompiler, ModulesContainer, and optional module overrides. lazy-module-loader.ts:12-19

Relationships

• IMPORTS → DynamicModule
• IMPORTS → Type

Used by

3 references from 2 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Injected or called by (1)

• LazyController — integration/lazy-modules/src/lazy.controller.ts:4

Imported by (2)

• AppModule — integration/lazy-modules/src/app.module.ts:7
• LazyController — integration/lazy-modules/src/lazy.controller.ts:4