在mongoose中的子文档mongodb中将对象添加到数组中。找不到属性“消息”

我有四个型号：teacher， student，teacherMessageSchema，studentMessageSchema。teacherMessageSchema是“教师 model in the消息：[teacherMessageSchema] property, andstudentMessageSchemais a subdocument in the学生 model in the消息：[studentMessageSchema] property. How to add an object to arrays[teacherMessageSchema] and[studentMessageSchema]”中的子文档。我试图这样做：

module.exports.sendMessage = (req, res) => {
    
    let {sender, receiver, msg} = req.body;
    var hex = /[0-9A-Fa-f]{6}/g;

    sender = (hex.test(sender))? mongoose.Types.ObjectId(sender) : sender;
    receiver = (hex.test(receiver))? mongoose.Types.ObjectId(receiver) : receiver;

    Teacher.findById({_id: receiver}, function(err, member) {
        console.log(member, 'member');

        member.messages.push({msg});

        console.log('messages', member.messages)
        
        member.save(function(err, updated) {
            if (err)
                res.send(err);
    
            res.json(updated, 'updated');
        });
    });
}

但是messages找不到该属性。

师生模型

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const crypto = require('crypto');
const {studentMessageSchema, teacherMessageSchema} = require('./message');


const userSchema = new Schema({
    name: {
        type: String,
        trim: true,
        required: true,
        maxLength: 32
    },
    email: {
        type: String,
        unique: true,
        trim: true,
        required: true,
        lowercase: true
    }
}, {timestamps: true});


const studentSchema = userSchema.clone();
studentSchema.add({
    messages : [studentMessageSchema]
});

const teacherSchema = userSchema.clone();
teacherSchema.add({
    messages : [teacherMessageSchema]
});



const User =  mongoose.model('User', userSchema);
const Student = mongoose.model('Student', studentSchema);
const Teacher = mongoose.model('Teacher', teacherSchema);

module.exports = {
    User,
    Student,
    Teacher
}

讯息模型

const mongoose = require('mongoose');
const Schema = mongoose.Schema;


const messageSchema = new Schema({
    "contentInfo" : {
        "viewed" : {type: Boolean, default: false},
        "msg" : {type: String, required: true},
        "createdAt" : { type : Date, default: Date.now }
    }
});

const studentMessageSchema = messageSchema.clone();
studentMessageSchema.add({
    "receiver" : {
        type: Schema.ObjectId
    }
});

const teacherMessageSchema = messageSchema.clone();
teacherMessageSchema.add({
    "sender" : {
        type: Schema.ObjectId
    }
});


module.exports = {
    messageSchema,
    teacherMessageSchema,
    studentMessageSchema
}

控制器消息

const User = require('../models/user');
const Student = require('../models/user');
const Teacher = require('../models/user');
const mongoose = require('mongoose');

module.exports.sendMessage = (req, res) => {
    
    let {sender, receiver, msg} = req.body;
    var hex = /[0-9A-Fa-f]{6}/g;

    sender = (hex.test(sender))? mongoose.Types.ObjectId(sender) : sender;
    receiver = (hex.test(receiver))? mongoose.Types.ObjectId(receiver) : receiver;

    Teacher.findById({_id: receiver}, function(err, member) {
        console.log(member, 'member');

        member.messages.push({msg});

        console.log('messages', member.messages)
        
        member.save(function(err, updated) {
            if (err)
                res.send(err);
    
            res.json(updated, 'updated');
        });
    });
}