var filename    = req.files.file.name;
            var tmpFilepath="./upload/"+ guid();
            fs.rename(req.files.file.path,tmpFilepath);
            fs.createReadStream(tmpFilepath)
              .on('end', function() {
             console.log("file Saved");
              })
              .on('error', function() {
               console.log("error encountered");
               // res.send('ERR');
              })
              // and pipe it to gfs
              .pipe(writestream);
                writestream.on('close', function (file) {
                fs.unlink(tmpFilepath);

              });