NestJS – File Upload

NestJS

File Upload

Handling single and multiple file uploads in NestJS using Multer.

File Upload Controller: Using FileInterceptor and FilesInterceptor to handle file uploads.

📄upload.controller.ts
typescript

import { Controller, Post, UseInterceptors, UploadedFile, UploadedFiles } from '@nestjs/common';
import { FileInterceptor, FilesInterceptor } from '@nestjs/platform-express';
import { multerOptions } from './multer.config';

@Controller('upload')
export class UploadController {
  
  @Post('single')
  @UseInterceptors(FileInterceptor('file', multerOptions))
  uploadSingleFile(@UploadedFile() file: Express.Multer.File) {
    return {
      message: 'File uploaded successfully',
      file: file.filename,
      path: file.path,
    };
  }

  @Post('multiple')
  @UseInterceptors(FilesInterceptor('files', 10, multerOptions))
  uploadMultipleFiles(@UploadedFiles() files: Array<Express.Multer.File>) {
    const uploadedFiles = files.map(file => ({
      filename: file.filename,
      path: file.path,
    }));
    
    return {
      message: 'Files uploaded successfully',
      files: uploadedFiles,
    };
  }
}

Multer Configuration: Setting up local storage options with destination and filename generation.

📄multer.config.ts
typescript

import { diskStorage } from 'multer';
import { extname } from 'path';

export const multerOptions = {
  storage: diskStorage({
    destination: './uploads',
    filename: (req, file, cb) => {
      // Generate a unique filename using timestamp and a random string
      const uniqueSuffix = Date.now() + '-' + Math.round(Math.random() * 1e9);
      const ext = extname(file.originalname);
      cb(null, `${file.fieldname}-${uniqueSuffix}${ext}`);
    },
  }),
  fileFilter: (req: any, file: any, cb: any) => {
    // Only allow specific file types (e.g., images)
    if (file.mimetype.match(/\/(jpg|jpeg|png|gif)$/)) {
      cb(null, true);
    } else {
      cb(new Error('Unsupported file type'), false);
    }
  },
  limits: {
    fileSize: 5 * 1024 * 1024, // 5MB limit
  },
};