javascript - node.js axios download file stream and writeFile

Question

i want download a pdf file with axios and save on disk (server side) with fs.writeFile, i have tried:

axios.get('https://xxx/my.pdf', {responseType: 'blob'}).then(response => {
    fs.writeFile('/temp/my.pdf', response.data, (err) => {
        if (err) throw err;
        console.log('The file has been saved!');
    });
});

the file is saved but the content is broken...

how do I correctly save the file?

Answer 1

Actually, I believe the previously accepted answer has some flaws, as it will not handle the writestream properly, so if you call "then()" after Axios has given you the response, you will end up having a partially downloaded file.

This is a more appropriate solution when downloading slightly larger files:

export async function downloadFile(fileUrl: string, outputLocationPath: string) {
  const writer = createWriteStream(outputLocationPath);

  return Axios({
    method: 'get',
    url: fileUrl,
    responseType: 'stream',
  }).then(response => {

    //ensure that the user can call `then()` only when the file has
    //been downloaded entirely.

    return new Promise((resolve, reject) => {
      response.data.pipe(writer);
      let error = null;
      writer.on('error', err => {
        error = err;
        writer.close();
        reject(err);
      });
      writer.on('close', () => {
        if (!error) {
          resolve(true);
        }
        //no need to call the reject here, as it will have been called in the
        //'error' stream;
      });
    });
  });
}

This way, you can call downloadFile(), call then() on the returned promise, and making sure that the downloaded file will have completed processing.

Or, if you use a more modern version of NodeJS, you can try this instead:

import * as stream from 'stream';
import { promisify } from 'util';

const finished = promisify(stream.finished);

export async function downloadFile(fileUrl: string, outputLocationPath: string): Promise<any> {
  const writer = createWriteStream(outputLocationPath);
  return Axios({
    method: 'get',
    url: fileUrl,
    responseType: 'stream',
  }).then(async response => {
    response.data.pipe(writer);
    return finished(writer); //this is a Promise
  });
}