nestjs-formdata-interceptor

nestjs-formdata-interceptor is a powerful library for NestJS that provides seamless interception and handling of multipart/form-data requests. This functionality is particularly beneficial for efficiently managing file uploads in your application.

Getting Started

Installation

To install nestjs-formdata-interceptor using npm:

npm install nestjs-formdata-interceptor

OR using yarn

yarn add nestjs-formdata-interceptor

Usage

To use nestjs-formdata-interceptor, import it into the main directory of your NestJS application and configure it as shown below:

import { NestFactory } from "@nestjs/core";
import { NestExpressApplication } from "@nestjs/platform-express";
import { AppModule } from "./app.module";
import {
  FormdataInterceptor,
  LocalFileSaver,
} from "nestjs-formdata-interceptor";

async function bootstrap() {
  const app = await NestFactory.create<NestExpressApplication>(AppModule);

  app.useGlobalInterceptors(
    new FormdataInterceptor({
      customFileName(context, originalFileName) {
        return `${Date.now()}-${originalFileName}`;
      },
      fileSaver: new LocalFileSaver({
        prefixDirectory: "./public",
        customDirectory(context, originalDirectory) {
          return originalDirectory;
        },
      }),
    }),
  );

  await app.listen(3000);
}
bootstrap();

Fastify

need to install @fastify/multipart package.

import { NestFactory } from "@nestjs/core";
import { AppModule } from "./app.module";
import {
  FastifyAdapter,
  NestFastifyApplication,
} from "@nestjs/platform-fastify";
import fastifyMultipart from "@fastify/multipart";
import {
  LocalFileSaver,
  FormdataInterceptor,
} from "nestjs-formdata-interceptor";

async function bootstrap() {
  const app = await NestFactory.create<NestFastifyApplication>(
    AppModule,
    new FastifyAdapter(),
  );
  app.register(fastifyMultipart);

  app.useGlobalInterceptors(
    new FormdataInterceptor({
      customFileName(context, originalFileName) {
        return `${Date.now()}-${originalFileName}`;
      },
      fileSaver: new LocalFileSaver({
        prefixDirectory: "./public",
        customDirectory(context, originalDirectory) {
          return originalDirectory;
        },
      }),
    }),
  );

  await app.listen(3000);
}
bootstrap();

OR

you can use route spesific interceptor

import { Body, Controller, Post, UseInterceptors } from "@nestjs/common";
import { AppService } from "./app.service";
import { CreateDto } from "./dto/create.dto";
import { FormdataInterceptor } from "nestjs-formdata-interceptor";

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Post()
  @UseInterceptors(new FormdataInterceptor())
  getHello(@Body() createDto: CreateDto) {
    // your controller logic
  }
}

Explanation

1. Custom File Name:

The customFileName function allows you to generate custom file names for each uploaded file. In the example above, the file name is prefixed with the current timestamp followed by the original file name.

2. File Saver:

• The LocalFileSaver is used to define the directory where the files will be saved.

  • prefixDirectory specifies the root directory where all files will be saved.
  • customDirectory allows you to specify a custom sub-directory within the root directory. By default, it uses the original directory provided.

Custom File Saver

If you need custom file-saving logic, implement the IFileSaver interface. Here's an example:

import { FileData, IFileSaver } from "nestjs-formdata-interceptor";
import { ExecutionContext } from "@nestjs/common";

export class CustomFileSaver implements IFileSaver {
  public save(
    fileData: FileData,
    context: ExecutionContext,
    args: unknown, // this will be get from save method payload
  ): any {
    // do your file save logic
    // and return the file save data
  }
}

Then, use your custom file saver in the interceptor configuration:

import { NestFactory } from "@nestjs/core";
import { NestExpressApplication } from "@nestjs/platform-express";
import { AppModule } from "./app.module";
import { FormdataInterceptor } from "nestjs-formdata-interceptor";
import { CustomFileSaver } from "path-to-your-file-saver";

async function bootstrap() {
  const app = await NestFactory.create<NestExpressApplication>(AppModule);

  app.useGlobalInterceptors(
    new FormdataInterceptor({
      customFileName(context, originalFileName) {
        return `${Date.now()}-${originalFileName}`;
      },
      fileSaver: new CustomFileSaver(),
    }),
  );

  await app.listen(3000);
}
bootstrap();

File Validation

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

import { IsArray, IsNotEmpty } from "class-validator";
import {
  FileData,
  LocalFileData,
  HasMimeType,
  IsFileData,
  MaxFileSize,
  MimeType,
  MinFileSize,
} from "nestjs-formdata-interceptor";

export class CreateDto {
  @IsArray()
  @IsNotEmpty()
  @IsFileData({ each: true })
  @HasMimeType([MimeType["video/mp4"], "image/png"], { each: true })
  @MinFileSize(2000000, { each: true })
  @MaxFileSize(4000000, { each: true })
  // array file
  files: LocalFileData[];

  @IsFileData()
  @IsNotEmpty()
  @HasMimeType([MimeType["video/mp4"], "image/png"])
  @MinFileSize(2000000)
  @MaxFileSize(4000000)
  // single file
  file: LocalFileData;

  @IsFileData()
  @IsNotEmpty()
  @HasMimeType([MimeType["video/mp4"], "image/png"])
  @MinFileSize(2000000)
  @MaxFileSize(4000000)
  /**
   * customize file data save method
   * @param args [string] the payload sent to the custom file saver
   * @returns [Promise<string>] the file path where the file was saved
   * */
  customizeFileData: FileData<Promise<string>, string>;
}

Controller

Define your controller to handle file uploads:

import { Body, Controller, Post } from "@nestjs/common";
import { AppService } from "./app.service";
import { CreateDto } from "./dto/create.dto";

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Post()
  async getHello(@Body() createDto: CreateDto) {
    // save single file
    createDto.file.save(); // by default the file save data type is string

    // custom the file path on save function
    createDto.file.save({ path: "/custom-path" }); // This path will be appended to the prefix directory if it is set.

    // save multiple file
    createDto.files.map((file) => file.save()); // by default the file save data type is string

    // customize file data example
    await createDto.customizeFileData.save("bucket_name"); // it will be returning Promise<string>
  }
}

With this setup, nestjs-formdata-interceptor will manage multipart/form-data requests efficiently, allowing for structured handling of file uploads in your NestJS application.

Contributors

License

MIT