I am writing this, mostly to myself as a reminder on how to do it. The documentation for node and expressjs in general is really quite bad. They really expect everybody to basically read the JavaScript and learn through the code.

So this post is on how to submit a file using a multipart form request and how to manipulate the file on the server side once it's been sent. The first thing to know is that in the most recent versions of expressjs and nodejs (as of this writing), you don't need any other tools like connect-form or various others that do the same thing in order to parse the multipart request.

If your form element has a name attribute called "upload", then in the req object passed into the route function, you'll have a files object. This files object acts as a dictionary for the form inputs of type file. In my case, <input type="file" name="upload"> you will end up seeing the following if you did a console.dir(req.files.upload);

{
  upload: {
    size: 332853,
    path: '/private/tmp/test/uploads/ef8037ea95188bef1f0b2e88dc4d1294.jpg',
    name: '26159.jpg',
    type: 'image/jpeg',
    lastModifiedDate: Wed, 14 Dec 2011 08: 30: 41 GMT,
    _writeStream: {
      path: '/private/tmp/test/uploads/ef8037ea95188bef1f0b2e88dc4d1294.jpg',
      fd: 8,
      writable: false,
      flags: 'w',
      encoding: 'binary',
      mode: 438,
      bytesWritten: 332853,
      busy: false,
      _queue: [],
      drainable: true
    },
    length: [Getter],
    filename: [Getter],
    mime: [Getter]
  }
}

Looking carefully at the above output, you'll see that an object literal with many interesting properties was assigned as the value of req.files.upload. If I add another input with the same name, it becomes an array of these same properties as seen below. Before you ask, yes the file names in the 'name' field are correct. They weren't nicely named to begin with.

{
  upload: [
    {
      size: 206727,
      path: '/private/tmp/test/uploads/854573a2aad50ce26eaf775d6ec53353.jpg',
      name: '44905_uGR2j-f7d482888874046f92b93801df9a37e2-3.jpg',
      type: 'image/jpeg',
      lastModifiedDate: Wed, 14 Dec 2011 08: 45: 09 GMT,
      _writeStream: [Object],
      length: [Getter],
      filename: [Getter],
      mime: [Getter]
    },
    {
      size: 360499,
      path: '/private/tmp/test/uploads/991c1680134ee162f50330f6c1c2d53f.jpg',
      name: '89933_NV8Jd-291d372b2d1e0f6813e60ffebd2c9baf.jpg',
      type: 'image/jpeg',
      lastModifiedDate: Wed, 14 Dec 2011 08: 45: 09 GMT,
      _writeStream: [Object],
      length: [Getter],
      filename: [Getter],
      mime: [Getter]
    }
  ]
}

In order to know where these files will be saved, you need to specify it in your app.js file for express. I created a directory called uploads in the root of my project and pointed the uploaded files directory here. I also told the bodyParser() to keep the file name extensions from the original file name.

To do this, change the code from:

app.use(express.bodyParser());

to this code:

  app.use(express.bodyParser({
    uploadDir: __dirname + '/uploads',
    keepExtensions: true
  }));

This alone is enough to get you started. Remember to add the encoding type to your form element in the html. Without out, you won't get anything but a file name string.

<form action="/sendfile" method="POST" enctype="multipart/form-data">

Feel free to leave questions or comments and I'll update this accordingly.

I was playing Fallout New Vegas last night after a sizable break. I spent a couple of hours getting my visual mods to work the way that I want them to. I've still not beaten the game so I am not quite ready to use some of the more drastic mods that the affect the built-in hardcore mode or greater story arc. I am an avid Fallout 3/NV fan. I think Bethesda really did a phenomenal job with Fallout 3 despite the whining I hear from the creators and fans of Fallout 1 and 2 which were good games as well.

The more I play however, the more I feel inclined to jump back into scripting my own mods for the game. For me it feels like a foot step into the gaming industry which is also something I want. More on this later as well as some modding ideas.