InstanceLoader

Kind: Class

Source: packages/core/injector/instance-loader.ts

Part of: Core

InstanceLoader coordinates the creation of provider, controller, and injectable instances for modules registered in the dependency injection container. During application bootstrap, it delegates dependency resolution to the injector and can report initialization progress through a configured logger.

Methods

When something fails

• InstanceLoader handles failure in 1 place: it lets it reach the caller in all 1.

Diagram

mermaid
graph LR
  A[Application Bootstrap] --> B[InstanceLoader]
  B --> C[Container Modules]
  B --> D[Injector]
  B --> E[Logger]
  C --> F[Providers]
  C --> G[Injectables]
  C --> H[Controllers]
  D --> F
  D --> G
  D --> H

Usage

ts
import { InstanceLoader } from '@nestjs/core/injector/instance-loader';
import { Injector } from '@nestjs/core/injector/injector';

// Typically created internally by the Nest application bootstrap process.
const instanceLoader = new InstanceLoader(
  container,
  new Injector(),
  graphInspector,
);

instanceLoader.setLogger(logger);

// Resolves and creates providers, injectables, and controllers
// for all modules in the container.
await instanceLoader.createInstancesOfDependencies();

AI Coding Instructions

• Treat InstanceLoader as a bootstrap-level internal service; application code should normally rely on Nest's standard application factory instead of constructing it directly.
• Ensure modules are registered in the container before calling createInstancesOfDependencies().
• Preserve the dependency creation order: providers and injectables must be available before controllers are instantiated.
• Use setLogger() to integrate bootstrap progress reporting without coupling instance creation logic to a specific logger implementation.
• Keep dependency resolution delegated to Injector; avoid adding direct constructor-resolution logic to InstanceLoader.

Relationships

• IMPORTS → Logger
• IMPORTS → LoggerService
• IMPORTS → Controller
• IMPORTS → Injectable

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• TestingInstanceLoader — packages/testing/testing-instance-loader.ts:6