Problems in writing binary data with node.js

Question

I am trying to write the binary body of a request to a file and failing. The file is created on server but I am unable to open it. I am getting 'Fatal error: Not a png' on Ubuntu. Here is how I am making the request:

curl --request POST --data-binary "@abc.png" 192.168.1.38:8080

And here is how I am trying to save it with the file. The first snippet is a middleware for appending all the data together and second one is the request handler:

Middleware:

app.use(function(req, res, next) {
  req.rawBody = '';
  req.setEncoding('utf-8');
  req.on('data', function(chunk) { 
    req.rawBody += chunk;
  });
  req.on('end', function() {
    next();
  });
});

Handler:

exports.save_image = function (req, res) {
  fs.writeFile("./1.png", req.rawBody, function(err) {
    if(err) {
      console.log(err);
    } else {
      console.log("The file was saved!");
    }
  });
  res.writeHead(200);
  res.end('OK\n');
};

Here's some info which might help. In the middleware, if I log the length of rawBody, it looks to be correct. I am really stuck at how to correctly save the file. All I need is a nudge in the right direction.

Answer 1

Here is a complete express app that works. I hit it with curl --data-binary @photo.jpg localhost:9200 and it works fine.

var app = require("express")();
var fs = require("fs");
app.post("/", function (req, res) {
  var outStream = fs.createWriteStream("/tmp/upload.jpg");
  req.pipe(outStream);
  res.send();
});
app.listen(9200);

I would just pipe the request straight to the filesystem. As to your actual problem, my first guess is req.setEncoding('utf-8'); as utf-8 is for text data not binary data.

Answer 2

For fix your code: I'm with @Peter Lyons, that the error is probably the req.setEncoding('utf-8'); line.

I know the following don't ask your question directly, but proposes an alternative to it by using req.files functionality provided by Express.js, which you are using.

if (req.files.photo && req.files.photo.name) { // Get the temporary location of the file. var tmp_path = req.files.photo.path;

// set where the file should actually exists - in this case it is in the "images" directory.
var target_path = './public/profile/' + req.files.photo.name;

// Move the file from the temporary location to the intended location.
fs.rename(tmp_path, target_path, function (error) {
    if (!error) {
        /*
         * Remove old photo from fs.
         * You can remove the following if you want to.
         */
        fs.unlink('./public/profile/' + old_photo, function () {
            if (error) {
                callback_parallel(error);
            }
            else {
                callback_parallel(null);
            }
        });
    }
    else {
        callback_parallel(error);
    }
});

}