How to use the multer.diskStorage function in multer

// check for *.ipynb extension
    if (/\.ipynb$/.test(file.originalname)) {
        cb(null, true);
    } else {
        cb(new Error('Wrong file extension. Make sure to upload a Jupyter Notebook file (*.ipynb).'));
    }
}

var limits = {
    fields: 0,
    files: 1,
    parts: 1
};

// Use multer disk storage to write uploaded file
var storage = multer.diskStorage({
    destination: destination,
    filename: filename
});
module.exports = multer({
    storage: storage,
    fileFilter: fileFilter,
    limits: limits
});

console.log(req.body.email);
    // move
    var destPath = '/root/Public/QuickNote/public/cloud/'+req.body.email+'/'+videoName;
    var relPath = '/cloud/'+req.body.email+'/'+videoName;
    fs.rename(tmpPath+videoName,destPath, function(err){
        if(err){
            throw err;
        }
    });
    res.json({code: 200, path: relPath});


});

var audioName;
var audioStorage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, tmpPath);
    },
    filename: function (req, file, cb) {
        var date = new Date();
        audioName  = "Audio-Recording-"+date.format("yyyy-MM-dd-hh-mm-ss")+".wav";
        cb(null, audioName);
    }
});
var audioUpload = multer({storage: audioStorage});

app.post("/uploadAudio", audioUpload.any(), function(req, res) {
    console.log("audio upload received");
    // move
    var destPath = '/root/Public/QuickNote/public/cloud/'+req.body.email+'/'+audioName;
    var relPath = '/cloud/'+req.body.email+'/'+audioName;

const   express     = require("express");
const   { ObjectID } = require("mongodb");
const   moment      = require("moment");
const   multer      = require("multer");
const   mime        = require("mime-types");
const   path        = require("path");
const   crypto      = require("crypto");
const   User        = require("../models/user");
const   middleware  = require("../middleware/index");
const   Channel     = require("../models/channel");

const       router = express.Router();

const upload = multer({
    storage: multer.diskStorage({
        destination: path.join(__dirname, "../public/files/image"),
        filename: (req, file, cb)=>{
            crypto.pseudoRandomBytes(4, (err, raw)=>{
                const mimeType = mime.lookup(file.originalname);
                // throw away any extension if provided
                const nameSplit = file.originalname.split(".").slice(0, -1);
                // nameSplit.pop();

                // replace all white spaces with - for safe file name on different filesystem
                const name = nameSplit.join(".").replace(/\s/g, "-");
                cb(null, raw.toString("hex") + name + "." + mime.extension(mimeType));
            });
        },
    }),
});

var express = require("express");
var router  = express.Router();
var Campground = require("../models/campground");
var middleware = require("../middleware");
var request = require("request");
var multer = require('multer');
var storage = multer.diskStorage({
  filename: function(req, file, callback) {
    callback(null, Date.now() + file.originalname);
  }
});
var imageFilter = function (req, file, cb) {
    // accept image files only
    if (!file.originalname.match(/\.(jpg|jpeg|png|gif)$/i)) {
        return cb(new Error('Only image files are allowed!'), false);
    }
    cb(null, true);
};
var upload = multer({ storage: storage, fileFilter: imageFilter})

var cloudinary = require('cloudinary');
cloudinary.config({ 
  cloud_name: 'learntocodeinfo',

if (process.env['NEWRELIC_LICENSE']) require('newrelic');
var express = require('express');
var passport = require('passport');
var request = require('request');
var multer  = require('multer');
var async = require('async');

var cinco = require("../lib/api");

var router = express.Router();

var storageLogoCompany = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, 'public/uploads')
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname)
  }
});
var uploadLogoCompany = multer({ storage: storageLogoCompany });
var cpUploadLogoCompany = uploadLogoCompany.fields([
  {name: 'logoCompany', maxCount: 1},
  {name: 'board_headshot', maxCount: 1 },
  {name: 'technical_headshot', maxCount: 1 },
  {name: 'marketing_headshot', maxCount: 1 },
  {name: 'finance_headshot', maxCount: 1 },
  {name: 'other_headshot', maxCount: 1 }
]);

admin.post('/mods', (req, res, next)=>{
    var storage = multer.diskStorage({
        destination: (req, file, callback)=>{
            callback(null, paths.mods);
        },
        filename: (req, file, callback)=>{
            callback(null, file.originalname);
        }
    });
    var upload = multer({storage: storage}).single('file');
    upload(req, res, (err)=>{
        if (err) {
            return next(err);
        }
        res.setHeader('Refresh', '1;.')
        res.redirect(201, '.');
    });
});

export const getRoutes = ({
  puppeteerProvider,
  getMetrics,
  getConfig,
  getPressure,
  workspaceDir,
  disabledFeatures,
}: IGetRoutes): Router => {
  const router = Router();
  const storage = multer.diskStorage({
    destination: (_req, _file, cb) => {
      cb(null, workspaceDir);
    },
    filename: (_req, file, cb) => {
      cb(null, file.originalname);
    },
  });
  const upload = multer({ storage }).any();
  const config = getConfig();

  if (!disabledFeatures.includes(Feature.INTROSPECTION_ENDPOINT)) {
    router.get('/introspection', (_req, res) => res.json(hints));
  }
  if (!disabledFeatures.includes(Feature.METRICS_ENDPOINT)) {
    router.get('/metrics', async (_req, res) => res.json(await getMetrics()));
  }

//登录和注册需要的User类
var User = require('../models/user');
//发表需要的Post类
var Post = require('../models/post');
//引入留言需要的Comment类
var Comment = require('../models/comment');
//需要引入一个加密的模块
var crypto = require('crypto');
//引入multer插件
var multer = require('multer');
//插件的配置信息
var storage = multer.diskStorage({
    //这个是上传图片的地址.
    destination:function(req,file,cb){
        cb(null,'public/images')
    },
    //上传到服务器上图片的名字.
    filename:function(req,file,cb){
        cb(null,file.originalname)
    }
})
var upload = multer({storage:storage,size:10225});

//一个权限的问题？
//1.用户未登录的情况下，是无法访问/post ,/logout的
//2.用户在登录的情况下，是无法访问/login,/reg 的
//那么，如果才能完成这个权限的问题呢？

return res.status(500).json({
              title: 'An error occured',
              error: err
            });
          }
          res.status(200).json({
            message: 'Form is deleted',
            obj: result
          });
        })
      });
    }
  }
);

var storage = multer.diskStorage({
  destination: function (req, file, cb) {
    if (req.user.role[0] === "admin") {
    Form.findById((req.params.id), function (err, form){
      if (err) {
        throw err;
      }
    var dest = 'server/uploads/forms/' + form.owner;
    var stat = null;
    try {
      stat = fs.statSync(dest);
    }
    catch (err) {
      fs.mkdirSync(dest);
    }
    if (stat && !stat.isDirectory()) {
      throw new Error('Directory cannot be created because an inode of a different type exists at "' + dest + '"');