JSON Zip Response in node.js

Question

I'm pretty new to node.js and I'm trying to send back a zip file containing JSON results. I've been trying to figure it out how to do it, but haven't had the expected results.

I'm using NodeJS, ExpressJS, LocomotiveJS, Mongoose and MongoDB.

Since we're building a mobile oriented application, I'm trying to save as many as bandwith as I can.

The daily initial load for the mobile app could be a big JSON document, so I want to zip it before sending it to the device. If possible I'd like to do it everything in memory in order to avoid disk I/O.

I tried with 3 libraries so far:

• adm-zip
• node-zip
• zipstream

The best result I achieved is using node-zip. Here's my code:

  return Queue.find({'owners': this.param('id')}).select('name extra_info cycle qtype purge purge_time tasks').exec(function (err, docs) {
    if (!err) {
      zip.file('queue.json', docs);
      var data = zip.generate({base64:false,compression:'DEFLATE'});

      res.set('Content-Type', 'application/zip');
      return res.send(data);
    }
    else {
      console.log(err);
      return res.send(err);
    }
  });

The result is a downloaded zip file but the content is unreadable.

I'm pretty sure I'm mixing up things, but to this point I'm not sure how to proceed.

Any advise?

Thanks in advace

Answer 1

You can compress output in express 3 with this:

app.configure(function(){
  //....
  app.use(express.compress());
});


app.get('/foo', function(req, res, next){
  res.send(json_data);
});

If the user agent supports gzip it will gzip it for you automatically.