Node.js how to pipe gzip stream to writestream

Question

Node.js how to pipe gzip stream to writestream

I can't seem to get this to work. I want to write some data to a gzip stream and then pipe the gzip stream to a file write stream. I want to then call a function when the files done writing. I currently have:

  var gz = zlib.createGzip()
               .pipe(fs.createWriteStream(gz_path));

  gz.write(data);

  gz.on('error', function(err){
    console.log("wtf error", err);
  });

  gz.on('finish', function(){
    console.log("write stream is done");
    dosomething();
  });

The finish event or the error event is never called.

javascript
node.js

Answer 1

try

var zlib = require('zlib');
var stream = require('stream');
var util = require('util');
var fs = require('fs');

var gz = zlib.createGzip();

function StringifyStream(){
    stream.Transform.call(this);

    this._readableState.objectMode = false;
    this._writableState.objectMode = true;
}
util.inherits(StringifyStream, stream.Transform);

StringifyStream.prototype._transform = function(obj, encoding, cb){
    this.push(JSON.stringify(obj));
    cb();
};


var data = "some data in here";

var rs = new stream.Readable({ objectMode: true });
rs.push(data);
rs.push(null);


rs.pipe(new StringifyStream())
  .pipe(gz)
  .pipe(fs.createWriteStream('test.gz'))
  .on('error', function(err){
    console.log("wtf error", err);
  })
  .on('finish', function(){
  console.log("write stream is done");
  // dosomething();
});