使用快速/ multer时更改文件名

var express = require( 'express' ),
    router  = express.Router(),
    util    = require( 'util' ),
    multer  = require( 'multer' );

var storage = multer.diskStorage(
    {
        destination: './uploads/',
        filename: function ( req, file, cb ) {
            //req.body is empty...
            //How could I get the new_file_name property sent from client here?
            cb( null, file.originalname+ '-' + Date.now()+".pdf");
        }
    }
);

var upload = multer( { storage: storage } );

router.route( '/upload' )
    .post( upload.single( 'file' ), post );

function post( request, response ) {

    response.json( { message: 'Files Uploaded!' } );

}