CODEWITHSUNDEEP
javascriptnode.js
arcade16
arcade16

Reputation: 1535

How to return zip file from node js api and handle on client side?

I have an API that creates a zip file using the archiver module in which I would like to pass back the zip as a respone and download it on the client side.

This is what my API that creates the zip looks like:

reports.get('/xxx/:fileName', async (req, res) => {

  var s3 = new AWS.S3();
  var archiver = require('archiver');

  var filenames = "xxx"
  var str_array = filenames.split(','); 

  for (var i = 0; i < str_array.length; i++) {

    var filename = str_array[i].trim();
    localFileName = './temp/' + filename.substring(filename.indexOf("/") + 1);

    file = fs.createWriteStream(localFileName, {flags: 'a', encoding: 'utf-8',mode: 0666});
    file.on('error', function(e) { console.error(e); });

    s3.getObject({
          Bucket: config.xxx,
          Key: filename
      })
      .on('error', function (err) {
          console.log(err);
      })
      .on('httpData', function (chunk) {
          file.on('open', function(){

            file.write(chunk);
          });
      })
      .on('httpDone', function () {
          file.end();
      })
      .send();
  }
    res.end("Files have been downloaded successfully")

    // create a file to stream archive data to.
    var output = fs.createWriteStream('example.zip');
    var archive = archiver('zip', {
      zlib: { level: 9 } // Sets the compression level.
    });

    // listen for all archive data to be written
    // 'close' event is fired only when a file descriptor is involved
    output.on('close', function() {
      console.log(archive.pointer() + ' total bytes');
      console.log('archiver has been finalized and the output file descriptor has closed.');
    });

    // This event is fired when the data source is drained no matter what was the data source.
    // It is not part of this library but rather from the NodeJS Stream API.
    // @see: https://nodejs.org/api/stream.html#stream_event_end
    output.on('end', function() {
      console.log('Data has been drained');
    });

    // good practice to catch warnings (ie stat failures and other non-blocking errors)
    archive.on('warning', function(err) {
      if (err.code === 'ENOENT') {
        // log warning
      } else {
        // throw error
        throw err;
      }
    });

    // good practice to catch this error explicitly
    archive.on('error', function(err) {
      throw err;
    });

    // pipe archive data to the file
    archive.pipe(output);

    // append files from a sub-directory, putting its contents at the root of archive
    archive.directory('./temp', false);

    // finalize the archive (ie we are done appending files but streams have to finish yet)
    // 'close', 'end' or 'finish' may be fired right after calling this method so register to them beforehand
    archive.finalize();

});

Also for reference here is another one of my APIs to show how I am accustomed to sending data back to the client:

reports.get('/xxx/:fileName', async (req, res) => {

  var s3 = new AWS.S3();

  var params = { 
    Bucket: config.reportBucket,
    Key: req.params.fileName,
    Expires: 60 * 5
  }

  try {
    s3.getSignedUrl('getObject', params, function (err, url) {
      if(err)throw err;
      res.json(url);
    });
  }catch (err) {
    res.status(500).send(err.toString());
  }
});

How can I send the zip back as a response and download it on the client side to disk?

Upvotes: 5

Views: 14508

Answers (2)

Thomas Jensen
Thomas Jensen

Reputation: 2765

Since archive is streaming, I would assume it can be pipe(lined) directly to the response (res):

// Node.js v10+, if res is a proper stream
const {pipeline} = require('stream')
pipeline(archive, res)

// Alternatively (search for caveats of pipe vs. pipeline)
archive.pipe(res)

You should probably set some HTTP headers on res to tell the browser the MIME type and possibly a filename:

res.set({
  'Content-Type': 'application/zip',
  'Content-Disposition': 'attachment; filename="zip"'
})

Upvotes: 7

Smily
Smily

Reputation: 3070

Okay so once you wrote your file, example.zip you can easily follow the example mentioned in another answer and do:

var stat = fileSystem.statSync('example.zip');

res.writeHead(200, {
    'Content-Type': 'application/zip',
    'Content-Length': stat.size
});

var readStream = fileSystem.createReadStream('example.zip');
// We replaced all the event handlers with a simple call to readStream.pipe()
readStream.pipe(res);

This should work perfectly. Credits to OP

Upvotes: 3

Related Questions