💭 Description

nestjs-form-data is a NestJS middleware for handling multipart/form-data, which is primarily used for uploading files.

• Process files and strings, serialize form-data to object
• Process files in nested objects
• Integration with class-validator, validate files with validator decorator

nestjs-form-data serializes the form-data request into an object and places it in the body of the request. The files in the request are transformed into objects.
Standard file storage types:

• Memory storage
• File system storage

Changelog

⏳ Installation

# npm
npm install nestjs-form-data
# yarn
yarn add nestjs-form-data

This module has class-validator and class-transformer as a required peed dependencies.
Read more about validation pipe in the official docs page.
Make sure that you already have these and enable global validation pipe:

# npm
npm install class-validator class-transformer
# yarn
yarn add class-validator class-transformer

Register a global validation pipe in main.ts file inside bootstrap function:

//main.ts
app.useGlobalPipes(
  new ValidationPipe({
    transform: true // Transform is recomended configuration for avoind issues with arrays of files transformations
  })
);

Add the module to your application

@Module({
  imports: [
    NestjsFormDataModule,
  ],
})
export class AppModule {
}

🪄 Usage

Apply @FormDataRequest() decorator to your controller method

@Controller()
export class NestjsFormDataController {


  @Post('load')
  @FormDataRequest()
  getHello(@Body() testDto: FormDataTestDto): void {
    console.log(testDto);
  }
}

If you are using class-validator describe dto and specify validation rules

export class FormDataTestDto {

  @IsFile()
  @MaxFileSize(1e6)
  @HasMimeType(['image/jpeg', 'image/png'])
  avatar: MemoryStoredFile;
  
}

Fastify

Need to install @fastify/multipart.

// main.ts
import { NestFactory } from '@nestjs/core';
import {
  FastifyAdapter,
  NestFastifyApplication,
} from '@nestjs/platform-fastify';
import multipart from '@fastify/multipart'

async function bootstrap() {
  const app = await NestFactory.create(
    AppModule,
    new FastifyAdapter()
  );

  app.register(multipart);

  await app.listen(3000);
}

Configuration

Static configuration

You can set the global configuration when connecting the module using the NestjsFormDataModule.config method:

@Module({
  imports: [
    NestjsFormDataModule.config({ storage: MemoryStoredFile }),
  ],
  controllers: [],
  providers: [],
})
export class AppModule {
}

Async configuration

Quite often you might want to asynchronously pass your module options instead of passing them beforehand. In such case, use configAsync() method, that provides a couple of various ways to deal with async data.

1. Use factory

NestjsFormDataModule.configAsync({
  useFactory: () => ({
    storage: MemoryStoredFile
  })
});

Our factory behaves like every other one (might be async and is able to inject dependencies through inject).

NestjsFormDataModule.configAsync({
 imports: [ConfigModule],
  useFactory: async (configService: ConfigService)  => ({
    storage: MemoryStoredFile,
    limits: {
      files: configService.get('files'),
    }
  }),
 inject: [ConfigService],
});

2. Use class

NestjsFormDataModule.configAsync({
  useClass: MyNestJsFormDataConfigService
});

Above construction will instantiate MyNestJsFormDataConfigService inside NestjsFormDataModule and will leverage it to create options object.

export class MyNestJsFormDataConfigService implements NestjsFormDataConfigFactory {
  configAsync(): Promise | FormDataInterceptorConfig {
    return {
      storage: FileSystemStoredFile,
      fileSystemStoragePath: '/tmp/nestjs-fd',
    };
  }
}

3. Use existing

NestjsFormDataModule.configAsync({
  imports: [MyNestJsFormDataConfigModule],
  useExisting: MyNestJsFormDataConfigService
});

It works the same as useClass with one critical difference - NestjsFormDataModule will lookup imported modules to reuse already created MyNestJsFormDataConfigService, instead of instantiating it on its own.

Method level configuration

Or pass the config object while using the decorator on the method

@Controller()
export class NestjsFormDataController {


  @Post('load')
  @FormDataRequest({storage: MemoryStoredFile})
  getHello(@Body() testDto: FormDataTestDto): void {
    console.log(testDto);
  }
}

Configuration fields

• isGlobal - If you want the module to be available globally. Once you import the module and configure it, it will be available globally
• storage - The type of storage logic for the uploaded file (Default MemoryStoredFile)
• fileSystemStoragePath - The path to the directory for storing temporary files, used only for storage: FileSystemStoredFile (Default: /tmp/nestjs-tmp-storage)
• cleanupAfterSuccessHandle - If set to true, all processed and uploaded files will be deleted after successful processing by the final method. This means that the delete method will be called on all files (StoredFile)
• cleanupAfterFailedHandle - If set to true, all processed and uploaded files will be deleted after unsuccessful processing by the final method. This means that the delete method will be called on all files (StoredFile)
• limits - busboy limits configuration. Constraints in this declaration are handled at the serialization stage, so using these parameters is preferable for performance.

File storage types

Memory storage

MemoryStoredFile The file is loaded into RAM, files with this storage type are very fast but not suitable for processing large files.

File system storage

FileSystemStoredFile The file is loaded into a temporary directory (see configuration) and is available during the processing of the request. The file is automatically deleted after the request finishes

Custom storage types

You can define a custom type of file storage, for this, inherit your class from StoredFile, see examples in the storage directory

Validation

By default, several validators are available with which you can check the file
Note: If you need to validate an array of files for size or otherwise, use each: true property from ValidationOptions

IsFile

Checks if the value is an uploaded file

@IsFile(validationOptions?: ValidationOptions)

IsFiles

Checks an array of files, the same as @IsFile({ each: true })
For convenience

@IsFiles(validationOptions?: ValidationOptions)

MaxFileSize

Maximum allowed file size

@MaxFileSize(maxSizeBytes: number, validationOptions?: ValidationOptions)

MinFileSize

Minimum allowed file size

@MinFileSize(minSizeBytes: number, validationOptions?: ValidationOptions)

HasMimeType

Check the mime type of the file
The library uses two sources to get the mime type for the file:

• file-type library gets mime-type: gets the mime-type from the magic number directly from the binary data, it is a reliable source because it checks the file itself but may not return values for some files
• content type header from [busboy](https://www.npmjs.com/package/busboy: is a less trusted source because it can be tampered with

Priority of receiving mime-type corresponds to the list

The default is simple mode, which does not check the data source, but you can pass a second argument to strictly check the mime-type and data source.
You can also get the mime type and data source via the get mimeTypeWithSource():MetaFieldSource getter on the StoredFile

type AllowedMimeTypes = Array
type AllowedMimeType = string | RegExp;

@HasMimeType(allowedMimeTypes: AllowedMimeTypes | AllowedMimeType, strictSource?: MetaSource | ValidationOptions, validationOptions?: ValidationOptions)

You can also use partial matching, just pass the unimportant parameter as *, for example:

@HasMimeType('image/*')

also as array:

@HasMimeType(['image/*', 'text/*'])

HasExtension

Check the extension type of the file The library uses two sources to get the extension for the file:

• file-type library gets mime-type: gets the extension from the magic number directly from the binary data, it is a reliable source because it checks the file itself but may not return values for some files
• value after the last dot in file name: is a less trusted source because it can be tampered with

Priority of receiving extension corresponds to the list

The default is simple mode, which does not check the data source, but you can pass a second argument to strictly check the extension and data source.
You can also get the extension and data source via the get extensionWithSource():MetaFieldSource getter on the StoredFile

@HasExtension(allowedMimeTypes: string[] | string, strictSource?: MetaSource | ValidationOptions, validationOptions?: ValidationOptions)

Examples

FileSystemStoredFile storage configuration

Controller

import { FileSystemStoredFile, FormDataRequest } from 'nestjs-form-data';

@Controller()
export class NestjsFormDataController {


  @Post('load')
  @FormDataRequest({storage: FileSystemStoredFile})
  getHello(@Body() testDto: FormDataTestDto): void {
    console.log(testDto);
  }
}

DTO

import { FileSystemStoredFile, HasMimeType, IsFile, MaxFileSize } from 'nestjs-form-data';


export class FormDataTestDto {

  @IsFile()
  @MaxFileSize(1e6)
  @HasMimeType(['image/jpeg', 'image/png'])
  avatar: FileSystemStoredFile;

}

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Validate the array of file

DTO

import { FileSystemStoredFile, HasMimeType, IsFiles, MaxFileSize } from 'nestjs-form-data';

export class FormDataTestDto {

  @IsFiles()
  @MaxFileSize(1e6, { each: true })
  @HasMimeType(['image/jpeg', 'image/png'], { each: true })
  avatars: FileSystemStoredFile[];

}

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License

MIT