busboy上传问题

使用busboy进行图片上传，表单其他字段怎么获取，

exports.userSet = function (req, res, next) {
    //1、验证字段
    //2、上传
    var photo = '';
    var busboy = new Busboy({ headers: req.headers });
    busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
        //这里是设置下载后目录的（我是这样理解的，实际也是这样，若有不对的欢迎指正）
        var saveTo = path.join(__dirname, '../public/uploads', path.basename(filename));
        photo = saveTo;
        file.pipe(fs.createWriteStream(saveTo));
    });
    busboy.on('finish', function () {
		  var school = req.body.school;
		  var user_id = req.body.user_id;
		  var hobby = req.body.hobby;
		  console.log('school= ' + school);
        UserSet.newAndSave(user_id, photo, hobby, school, function (err) {
			  if (err) {
				  return next(err);
			  }
			  res.redirect('/');
        });
    });
    return req.pipe(busboy);
}
\n``` 
怎么从req,body拿到其他的字段啊