MulterModuleAsyncOptions

Kind: Interface

Source: packages/platform-express/multer/interfaces/files-upload-module.interface.ts

Part of: Platform Express

MulterModuleAsyncOptions configures Multer asynchronously when registering NestJS file upload support. It allows upload options to be provided by an existing provider, a dedicated options factory class, or an inline factory function with dependency injection.

Properties

Diagram

mermaid
graph LR
  A[MulterModuleAsyncOptions] --> B[useExisting]
  A --> C[useClass]
  A --> D[useFactory]
  A --> E[inject]

  B --> F[MulterOptionsFactory]
  C --> F
  D --> G[MulterModuleOptions]
  E --> D
  F --> G
  G --> H[MulterModule.registerAsync]

Usage

ts
import { Module } from '@nestjs/common';
import {
  MulterModule,
  MulterModuleAsyncOptions,
  MulterOptionsFactory,
} from '@nestjs/platform-express';
import { ConfigService } from '@nestjs/config';
import { diskStorage } from 'multer';

const multerOptions: MulterModuleAsyncOptions = {
  inject: [ConfigService],
  useFactory: async (configService: ConfigService) => ({
    storage: diskStorage({
      destination: configService.get<string>('UPLOAD_DIRECTORY', './uploads'),
      filename: (_request, file, callback) => {
        callback(null, `${Date.now()}-${file.originalname}`);
      },
    }),
    limits: {
      fileSize: 5 * 1024 * 1024,
    },
  }),
};

@Module({
  imports: [MulterModule.registerAsync(multerOptions)],
})
export class AppModule {}

AI Coding Instructions

• Use exactly one configuration strategy: useExisting, useClass, or useFactory.
• Add required dependencies to inject when using useFactory; their order must match the factory function parameters.
• Return a valid MulterModuleOptions object from the factory, either synchronously or as a Promise.
• Prefer useExisting when an existing MulterOptionsFactory provider should be reused; use useClass when Nest should create a dedicated factory provider.
• Configure storage, file-size limits, and file filtering in the returned Multer options rather than directly in controllers.

How it works

MulterModuleAsyncOptions is the public TypeScript configuration shape accepted by MulterModule.registerAsync(). It extends only the imports member of ModuleMetadata; its remaining members select how the module resolves MulterModuleOptions. MulterModuleOptions is an alias for MulterOptions. files-upload-module.interface.ts:4 files-upload-module.interface.ts:16-25 multer.module.ts:30

• imports is optional through the inherited ModuleMetadata.imports member and is copied to the dynamic module’s imports field. files-upload-module.interface.ts:16-19 multer.module.ts:31-34
• useFactory may be a function with arbitrary injected arguments that returns MulterModuleOptions directly or as a promise. When present, it becomes the factory for the MULTER_MODULE_OPTIONS provider. files-upload-module.interface.ts:22-25 multer.module.ts:63-68
• inject supplies that factory’s dependency tokens. When useFactory is selected and inject is absent, the module uses an empty array. files-upload-module.interface.ts:25 multer.module.ts:63-68
• useExisting names an existing class-type token for a MulterOptionsFactory. The options provider injects that token and calls its createMulterOptions() method. That method may return options directly or asynchronously. files-upload-module.interface.ts:9-11 files-upload-module.interface.ts:20 multer.module.ts:70-75
• useClass names a class-type MulterOptionsFactory. In the absence of useExisting and useFactory, the module registers the class as a provider, injects it into the options provider, and calls createMulterOptions(). files-upload-module.interface.ts:9-11 files-upload-module.interface.ts:21 multer.module.ts:48-57 multer.module.ts:70-75

useFactory takes precedence when it is set: the options-provider construction checks it first. A set useExisting also prevents registration of useClass; the injected factory token then selects useExisting before useClass. multer.module.ts:48-49 multer.module.ts:63-75

All members declared directly by this interface are optional, and the visible implementation contains no explicit validation or thrown error for a configuration with none of useFactory, useExisting, or useClass. In that case, its class branch constructs a provider whose token and injection entry are undefined. files-upload-module.interface.ts:20-25 multer.module.ts:48-57 multer.module.ts:70-75

Calling registerAsync constructs a dynamic module that exports MULTER_MODULE_OPTIONS and adds a generated MULTER_MODULE_ID value provider. multer.module.ts:30-42