# Module **Kind:** Class **Source:** [`packages/core/injector/module.ts`](https://github.com/nestjs/nest/blob/master/packages/core/injector/module.ts#L44) **Part of:** [Core](subsystem-packages-core) `Module` is Nest’s internal runtime representation of an application module within the dependency-injection container. It registers the module itself, `ModuleRef`, application configuration, injectable classes, and custom providers so dependencies can be resolved within the module scope. ## Methods | Method | Signature | Returns | |---|---|---| | `addCoreProviders` | `addCoreProviders()` | `void` | | `addModuleRef` | `addModuleRef()` | `void` | | `addModuleAsProvider` | `addModuleAsProvider()` | `void` | | `addApplicationConfig` | `addApplicationConfig()` | `void` | | `addInjectable` | `addInjectable(injectable: Provider, enhancerSubtype: EnhancerSubtype, host: Type)` | `void` | | `addProvider` | `addProvider(provider: Provider)` | `InjectionToken` | | `addProvider` | `addProvider(provider: Provider, enhancerSubtype: EnhancerSubtype)` | `InjectionToken` | | `addProvider` | `addProvider(provider: Provider, enhancerSubtype: EnhancerSubtype)` | `void` | | `isCustomProvider` | `isCustomProvider(provider: Provider)` | `provider is | ClassProvider | FactoryProvider | ValueProvider | ExistingProvider` | | `addCustomProvider` | `addCustomProvider(provider: | ClassProvider | FactoryProvider | ValueProvider | ExistingProvider, collection: Map, enhancerSubtype: EnhancerSubtype)` | `void` | | `isCustomClass` | `isCustomClass(provider: any)` | `provider is ClassProvider` | | `isCustomValue` | `isCustomValue(provider: any)` | `provider is ValueProvider` | | `isCustomFactory` | `isCustomFactory(provider: any)` | `provider is FactoryProvider` | | `isCustomUseExisting` | `isCustomUseExisting(provider: any)` | `provider is ExistingProvider` | | `isDynamicModule` | `isDynamicModule(exported: any)` | `exported is DynamicModule` | | `addCustomClass` | `addCustomClass(provider: ClassProvider, collection: Map, enhancerSubtype: EnhancerSubtype)` | `void` | | `addCustomValue` | `addCustomValue(provider: ValueProvider, collection: Map, enhancerSubtype: EnhancerSubtype)` | `void` | | `addCustomFactory` | `addCustomFactory(provider: FactoryProvider, collection: Map, enhancerSubtype: EnhancerSubtype)` | `void` | | `addCustomUseExisting` | `addCustomUseExisting(provider: ExistingProvider, collection: Map, enhancerSubtype: EnhancerSubtype)` | `void` | | `addExportedProviderOrModule` | `addExportedProviderOrModule(toExport: Provider | string | symbol | DynamicModule)` | `void` | | `addCustomExportedProvider` | `addCustomExportedProvider(provider: | FactoryProvider | ValueProvider | ClassProvider | ExistingProvider)` | `void` | | `validateExportedProvider` | `validateExportedProvider(token: InjectionToken)` | `void` | | `addController` | `addController(controller: Type)` | `void` | | `assignControllerUniqueId` | `assignControllerUniqueId(controller: Type)` | `void` | | `addImport` | `addImport(moduleRef: Module)` | `void` | | `replace` | `replace(toReplace: InjectionToken, options: any)` | `void` | | `hasProvider` | `hasProvider(token: InjectionToken)` | `boolean` | | `hasInjectable` | `hasInjectable(token: InjectionToken)` | `boolean` | | `getProviderByKey` | `getProviderByKey(name: InjectionToken)` | `InstanceWrapper` | | `getProviderById` | `getProviderById(id: string)` | `InstanceWrapper | undefined` | | `getControllerById` | `getControllerById(id: string)` | `InstanceWrapper | undefined` | | `getInjectableById` | `getInjectableById(id: string)` | `InstanceWrapper | undefined` | | `getMiddlewareById` | `getMiddlewareById(id: string)` | `InstanceWrapper | undefined` | | `getNonAliasProviders` | `getNonAliasProviders()` | `Array< [InjectionToken, InstanceWrapper] >` | | `createModuleReferenceType` | `createModuleReferenceType()` | `Type` | ## Where it refuses work - `Module` stops the work with `RuntimeException` when `!this._providers.has(this._metatype)`. - `Module` stops the work with `InvalidClassException` when `!(type && isFunction(type) && type.prototype)`. - `Module` stops the work with an early return when `this.isCustomProvider(injectable)`. - `Module` stops the work with an early return when `(this.isTransientProvider(provider) || this.isRequestScopeProvider(provider)) && isAlread…`. - `Module` stops the work with an early return when `isString(provide) || isSymbol(provide)`. - `Module` stops the work with an early return when `this._providers.has(token)`. ## Diagram ```mermaid graph LR A[Module Metadata] --> B[Module Instance] B --> C[Core Providers] C --> C1[Module Class Provider] C --> C2[ModuleRef] C --> C3[ApplicationConfig] B --> D[addProvider] B --> E[addInjectable] D --> F{Custom Provider?} F -->|No| G[Class Provider Wrapper] F -->|Yes| H[Factory / Value / Existing / Class Provider] G --> I[Provider Registry] H --> I E --> J[Injectable Registry] ``` ## Usage ```ts import { Module as RuntimeModule } from '@nestjs/core/injector/module'; import { NestContainer } from '@nestjs/core/injector/container'; import { ApplicationConfig } from '@nestjs/core/application-config'; class UsersService { findAll() { return ['Ada', 'Grace']; } } class AppModule {} const applicationConfig = new ApplicationConfig(); const container = new NestContainer(applicationConfig); // RuntimeModule is typically created by Nest internally during scanning. const moduleRef = new RuntimeModule(AppModule, container); // Register a standard class provider. moduleRef.addProvider(UsersService); // Register a custom value provider. moduleRef.addProvider({ provide: 'API_URL', useValue: 'https://api.example.com', }); // Register an injectable used by framework features such as guards or pipes. moduleRef.addInjectable(UsersService); ``` ## AI Coding Instructions - Treat `Module` as an internal Nest container type; application code should usually register providers through the `@Module()` decorator instead. - Use `addProvider()` for both class providers and custom provider objects; custom providers are detected through `isCustomProvider()`. - Preserve provider tokens when adding or modifying registrations, since tokens are the keys used for dependency resolution. - Ensure new providers are associated with the correct module instance so module-scoped resolution and exports continue to work. - Do not remove the core-provider setup path: module classes, `ModuleRef`, and application configuration must remain registered for Nest runtime behavior. ## How it works `Module` is a mutable runtime record for one module metatype within the dependency-injection container. It stores the module class, container reference, an ID, imports, exports, providers, injectables, middleware wrappers, controller wrappers, and entry-provider tokens. [packages/core/injector/module.ts:44-77] The container creates it from a compiled module type, assigns its container token afterward, stores it in the container’s module map, and may mark it global, set its distance to `Number.MAX_VALUE`, and register it among global modules. [packages/core/injector/container.ts:163-184] ## Relationships - IMPORTS → `EnhancerSubtype` - IMPORTS → `ENTRY_PROVIDER_WATERMARK` - IMPORTS → `ClassProvider` - IMPORTS → `Controller` - IMPORTS → `DynamicModule` - IMPORTS → `ExistingProvider` - IMPORTS → `FactoryProvider` - IMPORTS → `Injectable` - IMPORTS → `InjectionToken` - IMPORTS → `NestModule` - IMPORTS → `Provider` - IMPORTS → `Scope` - IMPORTS → `Type` - IMPORTS → `ValueProvider` - IMPORTS → `randomStringGenerator` - IMPORTS → `isFunction` - IMPORTS → `isNil` - IMPORTS → `isObject` - IMPORTS → `isString` - IMPORTS → `isSymbol` - IMPORTS → `isUndefined` ## Used by 4 references from 4 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example. ### Imported by (4) - `ListenersController` — `packages/microservices/listeners-controller.ts`:45 - `TestingInjector` — `packages/testing/testing-injector.ts`:23 - `TestingInstanceLoader` — `packages/testing/testing-instance-loader.ts`:6 - `TestingModule` — `packages/testing/testing-module.ts`:26