问如何使用mongoose引用另一个模型中的模型？

EN

**Post Form Schema** 

const mongoose = require('mongoose');

const PostSchema = new mongoose.Schema({
    title: {
        type: String,
        required: true
    },
    body: {
        type: String,
        required: true,
    },
    date: {
        type: Date,
        default: Date.now,
        required: true,
    },
    submittedBy: { *(this is where I would like to get the user who submitted the form)*
        type: mongoose.Schema.Types.ObjectId, 
        ref: 'User',
    },
    extraInfo: {
        type: String,
        default: 'Other info goes here',
    }
})

const Post = mongoose.model('Post', PostSchema);
module.exports = Post;

**Users Form Schema**

const mongoose = require('mongoose');
const UserSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    },
    email: {
        type: String,
        required: true
    },
    password: {
        type: String,
        required: true
    },
    date: {
        type: Date,
        default: Date.now
    }
});

const User = mongoose.model('User', UserSchema);
module.exports = User;

const express = require('express');
const Post = require('../models/post');
const router = express.Router();
const {ensureAuthenticated} = require("../config/auth.js");

router.get('/', ensureAuthenticated, (req, res) => {
    res.render('newPost')
})

router.post('/', ensureAuthenticated, (req, res) => {
    const post = new Post(req.body);
    console.log(req.body)

    post.save()
    .then((result) => {
        res.redirect('/dashboard')
    })
    .catch((err) => {
        console.log(err)
    })
})

module.exports = router;