当我试图用日期重命名上传的图像时，一个错误被抛出，它显示“无法读取未定义的属性'isLoggedIn'”。

如果有人能解决这个问题，我会很高兴的。首先感谢Multer，我认为它会抛出一个错误，然后转到错误处理中间件。

下面是我的app.js常量path=require('path')；

const express = require('express');
const bodyParser = require('body-parser');
const mongoose = require('mongoose');
const session = require('express-session');
const MongoDBStore = require('connect-mongodb-session')(session);
const csrf = require('csurf');
const flash = require('connect-flash');
const multer = require('multer');

const errorController = require('./controllers/error');
const User = require('./models/user');

const MONGODB_URI =  'mongodb+srv://axxxxn:xxxxxx@cluster0-sm6lw.mongodb.net/sxhxoxxxp';

const app = express();
const store = new MongoDBStore({
  uri: MONGODB_URI,
  collection: 'sessions'
});
const csrfProtection = csrf();

const fileStorage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, 'images');
  },
  filename: (req, file, cb) => {
    cb(null, new Date().toISOString() + '-' + file.originalname );
  }
});


app.set('view engine', 'ejs');
app.set('views', 'views');

const adminRoutes = require('./routes/admin');
const shopRoutes = require('./routes/shop');
const authRoutes = require('./routes/auth');

app.use(bodyParser.urlencoded({ extended: false }));
app.use(multer({ storage: fileStorage }).single('image'));
app.use(express.static(path.join(__dirname, 'public')));
app.use(
  session({
    secret: 'my secret',
    resave: false,
    saveUninitialized: false,
    store: store
  })
);

app.use(csrfProtection);
app.use(flash());
app.use((req, res, next) => {
  res.locals.isAuthenticated = req.session.isLoggedIn;
  res.locals.csrfToken = req.csrfToken();
  next();

});
app.use((req, res, next) => {
  //throw new Error('Sync Dummy');
  if (!req.session.user) {
    return next();
  }
  User.findById(req.session.user._id)
    .then(user => {
      //throw new Error('Dummy');
      if(!user){
        return next()
      }
      req.user = user;
      next();
    })
    .catch(err => {
      next(new Error(err));
    });
});



app.use('/admin', adminRoutes);
app.use(shopRoutes);
app.use(authRoutes);

app.get('/500',  errorController.get500);
app.use(errorController.get404);

app.use((error, req, res, next) => {
  res.status(404).render('500', {
    pageTitle: 'Error 500',
    path: '/500',
    isAuthenticated: req.session.isLoggedIn
  });
});


mongoose
  .connect(MONGODB_URI)
  .then(result => {
    app.listen(3000);
    console.log('connected');
  })
  .catch(err => {
    console.log(err);
  });