DeepHashedModuleOpaqueKeyFactory

Kind: Class

Source: packages/core/injector/opaque-key-factory/deep-hashed-module-opaque-key-factory.ts

Part of: Core

DeepHashedModuleOpaqueKeyFactory creates stable opaque keys used by the NestJS container to identify module instances. Static modules receive a key based on a cached module ID and name, while dynamic modules include deeply serialized metadata and a hash so differently configured instances remain distinct.

Implements: ModuleOpaqueKeyFactory

Methods

Where it refuses work

• DeepHashedModuleOpaqueKeyFactory stops the work with an early return when this.moduleTokenCache.has(key).
• DeepHashedModuleOpaqueKeyFactory stops the work with an early return when moduleId.
• DeepHashedModuleOpaqueKeyFactory stops the work with an early return when isClass.
• DeepHashedModuleOpaqueKeyFactory stops the work with an early return when isSymbol(value).

Diagram

mermaid
graph LR
  A[Module class] --> B[getModuleId]
  A --> C[getModuleName]
  B --> D[Static module key]
  C --> D

  E[Dynamic module metadata] --> F[getStringifiedOpaqueToken]
  B --> G[Opaque token]
  C --> G
  E --> G
  G --> F
  F --> H[Hash]
  H --> I[Dynamic module key]

Usage

ts
import { DeepHashedModuleOpaqueKeyFactory } from '@nestjs/core/injector/opaque-key-factory/deep-hashed-module-opaque-key-factory';

class FeatureModule {}

const keyFactory = new DeepHashedModuleOpaqueKeyFactory();

// Produces a stable key for this module class during the factory lifetime.
const staticKey = keyFactory.createForStatic(FeatureModule);

// Produces a hash that includes dynamic module configuration.
const dynamicKey = keyFactory.createForDynamic(FeatureModule, {
  providers: [{ provide: 'FEATURE_OPTIONS', useValue: { enabled: true } }],
  exports: ['FEATURE_OPTIONS'],
});

console.log({ staticKey, dynamicKey });

AI Coding Instructions

• Use createForStatic() for regular module classes and createForDynamic() whenever module metadata affects container identity.
• Preserve the cached module ID behavior; generating a new ID per call would prevent equivalent module references from resolving consistently.
• Ensure dynamic metadata is serializable through the factory’s opaque-token stringification logic; functions and symbols require consistent representations.
• Do not rely on generated opaque keys as public application identifiers; they are internal container keys and may change between process runs.
• When extending module metadata, include identity-relevant configuration so distinct dynamic module registrations produce distinct keys.

Relationships

• IMPORTS → DynamicModule
• IMPORTS → Type
• IMPORTS → Logger
• IMPORTS → randomStringGenerator
• IMPORTS → isFunction
• IMPORTS → isSymbol