Uploads Formidable file objects to S3, save to redis

gistfile1.js

// Uploads Formidable file objects to S3, save to redis
//
// TODO - add image processing task

var fs = require('fs');
var s3 = require('knox').createClient();
var redis  = require('redis');
var client = redis.createClient();

function update( data, cb ){

  var hash = [ 'upload:'+ data.id ];

  for(var i in data){
    if( data.hasOwnProperty(i) ){
      hash.push(i);
      hash.push(data[i]);
    }
  }

  client.hmset(hash, function(err, status){
    cb(err, status, data);
  });

};

exports.process = function( file, data ){
  return new Process( file, data );
};

function Process( file, data ){
  this.file = file;
  this.data = data;

  var stream = fs.createReadStream( file.path );

  this.hash({ id: data.id }, stream );
  this.upload( file.name, stream );
}

Process.prototype.hash = function( data, stream ){
  var self = this;
  var buf = '';

  stream.on('data', function(data){
    buf += data;
  });

  stream.on('end', function(){
    var fileHash = crypto.createHash('md5');
    fileHash.update( buf );
    data.hash = fileHash.digest('hex').slice(0,8);

    update( data, function(err){
      if( err ){
        console.error('Error hashing:'+ err);
        console.trace();
      }
    });
  });
};

Process.prototype.upload = function( path, stream ){
  var self = this;

  var headers = {
    'Content-Length': this.file.size,
    'Content-Type': this.file.type
  };

  s3.putStream(stream, path, headers, function(err, res){
    if( err ){
      console.error('Error uploading: '+ err);
      console.trace();
      return;
    }

    res.on('end', function(){
      self.data.url = res.req.url;
      self.data.status = 'uploaded';
      self.data.modifiedAt = +new Date();

      update( self.data, function(err){
        client.publish('uploads', JSON.stringify(self.data)); 
        client.zadd('uploads:global', self.data.createdAt, 'upload:'+ self.data.id );
      });
    });
  });
};

The only thing that's not self-explanatory is the call to update on line 61: update is a light wrapper around redis.hmset()