Skipper in SailsJS (beta) image resize before upload - image

Question

I'm using SailsJS (beta). I'm trying to find a way to use graphicsmagick to take the stream parsed by Skipper in SailsJS-beta to resize the image before calling the Skipper-function req.file('inputName').upload().
My goal is to take my large, original image, and resize it before uploading it. Sails beta have introduced the Skipper-file-parser which are poorly documented (at least I don't understand it). Please help me understand how to resize the image before upload.
This works (code in my controller action):
req.file('fileName').upload('storedImage.png', function(err, files){
// File is now uploaded to storedImage.png
});
What I want is something like:
// Read the file stream into a file upload
var stream = req.file('fileName');
gm(stream).resize(200, 200).write('storedImage.png', function(err){
// File is now resized to 200x200 px and uploaded to storedImage.png
});
My problem is: how do I properly fetch the stream from req.file('fileName') to send it to gm?

Answer 1

This should work for you:
var Writable = require('stream').Writable;
var resize = require('image-resize-stream')(100); // Or any other resizer
// The output stream to pipe to
var output = require('fs').createWriteStream('storedImage.png');
// Let's create a custom receiver
var receiver = new Writable({objectMode: true});
receiver._write = function(file, enc, cb) {
file.pipe(resize).pipe(output);
cb();
};
Now in your action you just have to use your receiver:
req.file('fileName').upload(receiver, function(err, files){
// File is now resized to 100px width and uploaded to ./storedImage.png
});
I have a feeling that Skipper's API is going to change, a lot, but this will work for now (with v0.1.x).
UPDATE
Specifically, if using gm for resizing, it'll be something like this:
var gm = require('gm');
var Writable = require('stream').Writable;
// The output stream to pipe to
var output = require('fs').createWriteStream('storedImage.png');
// Let's create a custom receiver
var receiver = new Writable({objectMode: true});
receiver._write = function(file, enc, cb) {
gm(file).resize('200', '200').stream().pipe(output);
cb();
};

Answer 2

I had problems with #bredikhin solution so I dig deeper into this and found this thread very helpful: Uploading files using Skipper with Sails.js v0.10 - how to retrieve new file name
I just changed one line of his Uploader:
[...]
file.pipe(outputs);
[...]
into:
gm(file).resize(200, 200).stream().pipe(outputs);
and this does the trick.
I wrote this answer because it may be helpful for someone.