Download azure blob storage files as zipped folder

Question

I am using azure blob storage with Nest.js for file handling.

Below is the download code:

const blobClient = this.getBlobClient(url);
const downloadBlockBlobResponse = await blobClient.download();
return downloadBlockBlobResponse.readableStreamBody;

getBlobClient(fileName: string): BlockBlobClient {
    const blobClient = containerClient.getBlockBlobClient(fileName);
    return blobClient;
}

File downloading is working fine. But I need to download the file into a zipped folder and return the blob result.

How to do that using Nest.js?

Answer 1

I need to download the file into a zipped folder

You can use my Github link to get the code to download the file as a zip folder.

app.service.ts

import { Injectable } from '@nestjs/common';
import { BlobServiceClient} from '@azure/storage-blob';
import * as archiver from 'archiver';
import { Readable } from 'stream';
 
 
@Injectable()
export class BlobStorageService {
   private readonly blobServiceClient: BlobServiceClient;

  constructor() {
    this.blobServiceClient = BlobServiceClient.fromConnectionString("Your storage connection string");
  }

  async downloadFileAsZip(containerName: string, fileName: string): Promise<Readable> {
    const containerClient = this.blobServiceClient.getContainerClient(containerName);
    const blobClient = containerClient.getBlockBlobClient(fileName);
    const downloadBlockBlobResponse = await blobClient.download();

    const archive = archiver('zip', { zlib: { level: 9 } });
    const stream = Readable.from(downloadBlockBlobResponse.readableStreamBody);

    archive.append(stream, { name: fileName });
    archive.finalize();
    return archive;
  }
}

app.controller.ts

import { Controller, Get, Param, Res } from '@nestjs/common';
import { Response } from 'express';
import { BlobStorageService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly blobStorageService: BlobStorageService) {}

@Get(':container/:fileName')
  async downloadFileAsZip(@Param('container') container: string, @Param('fileName') fileName: string, @Res() res: Response) {
    const stream = await this.blobStorageService.downloadFileAsZip(container, fileName);
    res.set({
      'Content-Type': 'application/zip',
      'Content-Disposition': `attachment; filename=${fileName}.zip`,
    });
    stream.pipe(res);
  }
}

Output:

To fetch the file as a zip folder you can use the below request:

localhost:3000/<Your container name>/<Your file name>

Browser: