Busboy + GridFS + Express4

upload-controller.js

var Busboy = require('busboy'),
    Grid = require('gridfs-stream'),
    mongoose = require('mongoose'),
    router = module.exports = require('express').Router();

var gfs = new Grid(mongoose.connection.db, mongoose.mongo);

router
  .get('/:item/receipt/info', function(req, res, next){
          gfs.files.find({
              _id : req.item.receipt
          }).toArray(function(err, files){
              if(err) return next(err);
  
              if(files.length === 0){
                  return next(new Error('File does not exist'));
              }
  
              var file = files[0];
  
              res.json(200, file);
          });
      })
  
  .get('/:item/receipt', function(req, res, next){
          gfs.files.find({
              _id : req.item.receipt
          }).toArray(function(err, files){
              if(err) return next(err);
  
              if(files.length === 0){
                  return next(new Error('File metadata does not exist'));
              }
  
              var file = files[0];
  
              var rs = gfs.createReadStream({
                  _id : req.item.receipt
              });
  
              res.writeHead(200, {
                  'Content-Type' : file.contentType,
                  'Content-Length' : file.length
              });
  
              rs.pipe(res);
          });
      })
  
      .post('/:item/receipt', function(req, res, next){
  
          if(req.item.receipt){
              return res.json(400, {
                  detail : 'Item already has receipt.'
              });
          }
  
          var _returns = 0;
          var _files = 0;
          var _receipt = undefined;
          var _error = undefined;
  
          var _return = function(error){
              _returns++;
  
              if(error){
                  _error = error;
              }
  
              if(_returns === _files + 1){
                  if(_error){
                      res.json(500, {
                          detail : error
                      });
                  } else if(_files === 0){
                      res.json(400, {
                          detail : 'No file attached.'
                      });
                  } else {
                      res.json(200, {
                          _id : _receipt
                      });
                  }
              }
          };
  
          var busboy = new Busboy({
              headers: req.headers,
              limits : {
                  files : 1
                  //fileSize : 5242880 // 5mb
              }
          });
  
          busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
  
              if (fieldname === 'receipt') {
                  _files++;
  
                  var ws = gfs.createWriteStream({
                      mode: 'w',
                      content_type: mimetype,
                      filename: filename,
                      metadata: {
                          //Any props you want to add
                      }
                  });
  
  
                  ws.on('close', function (file) {
                      req.item.receipt = file._id;
  
                      req.item.save(function(err){
                          if(err){
                              console.error(err);
                              _return('Could not save file to db.');
                          } else {
                              _receipt = file._id;
                              _return();
                          }
                      });
                  });
  
  
                  file.pipe(ws);
  
              } else {
                  file.resume();
              }
          });
  
          busboy.on('finish', function(){
              _return();
          });
  
          req.pipe(busboy);
      })
  
      .delete('/:item/receipt', function(req, res, next){
          if(!req.item.receipt){
              return res.json(400, {
                  detail : 'Item does not have a receipt'
              });
          }
  
          gfs.remove({ _id : req.item.receipt }, function(err){
              if(err) return next(err);
  
              req.item.receipt = undefined;
  
              req.item.save(function(err){
                  if(err) return next(err);
  
                  res.json(200, req.item);
              });
          });
      });