问如何将给定的模型保存在数据库mongodb中的特定集合中？

EN

const mongoose = require('mongoose');
extend = require('mongoose-extend-schema');
const Schema = mongoose.Schema;

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



const studentSchema = extend(userSchema, {
    teachers: []   
});

const teacherSchema = extend(userSchema, {
    isActiveTutor: {
        type: Boolean,
        default: false
    }
})
  


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

module.exports = {
    User,
    Student,
    Teacher
}

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

const jwt = require('jsonwebtoken');
const nodemailer = require('nodemailer');
const expressJwt = require('express-jwt');


module.exports.signup =  (req, res) => {
    const {name, surname, email, password, initials, role} = req.body;

    Student.User.findOne({email}).exec((err, student) => {
        if (student) {
            return res.status(400).json({
                error: "Email is taken"
            })
        }
    }
}
        

module.exports.accountActivationStudent = (req, res) => {
    const {token} = req.body;

    if(token) {
        jwt.verify(token, process.env.JWT_ACCOUNT_ACTIVATION, function(err, decoded) {
            if(err) {
                console.log('JWT VERIFY IN ACCOUNT ACTIVATION ERROR', err);

                return res.status(401).json({
                    error: 'Expired link. Signup again'
                })
            }

            const {name, surname, email, password} = jwt.decode(token);

            const student = new Student.User ({name, surname, email, password});

            student.save((err, student) => {
                if(err) {
                    console.log('SAVE Student IN ACCOUNT ACTIVATION ERROR', err);

                    return res.status(401).json({
                        error: 'Error saving student in database. Try signup again'
                    });
                }

                return res.json({
                    message: 'Signup success. Please signin'
                });
            });
        });
    } else {
            return res.json({
                message: 'Something went wrong. Try again'
            })
    }
};