对子文档发出 POST 请求时返回未定义？ mongoose，快递

Question

I'm trying a to make a post request to save new data to one of my subdocuments, but I'm getting an error when trying to access the subdocument in the function. It keeps coming back as undefined. How can I get a specific user by id and create and add new data the one it's subdocuments?

model

const mongoose = require("mongoose");

const Schema = mongoose.Schema;

const ClassworkSchema = new Schema({
    name: String,
    time: Date,
    todo: String,
    isDone: false
});

const OutcomesSchema = new Schema({
    name: String,
    time: Date,
    todo: String, 
    isDone: false,
    isApproved: false
})

const MeetupSchema = new Schema({
    name: String,
    time: Date,
    location: String,
    attended: false
})
const UserSchema = new Schema({
    name: {
      type: String,
      required: true
    },
    email: {
      type: String,
      required: true
    },
    password: {
      type: String,
      required: true
    },
    date: {
      type: Date,
      default: Date.now
    },
    classwork:{type: [ClassworkSchema], default: []},
    outcomes: [OutcomesSchema],
    meetups: [MeetupSchema],
  });



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

controller

  classworkRouter.post("/:userId/", (req, res) => {
  User.findById(req.params.user_id, (err, user) => {
    if (err) return err;

    new_classwork = new classwork();
    (new_classwork.name = req.body.name),
      (new_classwork.date = req.body.date),
      (new_classwork.todo = req.body.todo),
      (new_classwork.isDone = req.body.isDone);
    console.log(new_classwork);

    user.classwork = {};
    user.classwork.name = req.body.classwork.name;
    user.classwork.todo = user.classwork.todo;

    if (user.classwork === undefined) {
      user.classwork.push(new_classwork);
    } else {
      user.classwork = [new_classwork];
    }

    user.save(function (err, data) {
      if (err) res.send(err);

      res.json({ message: "work added", data: data });
    });
  });
});

you can see the error in the terminal in the following phto:

Answer 1

in this part of code

new_classwork = new classwork()

you shoud defined the new_classwrok like this:

let new_classwork = new classwork()

and new classwork() is not defined, you must to require Model of classwork in controller..

in schema file export schemas like this:

const User = mongoose.model('users', UserSchema);
const Classwork = mongoose.model('Classwork', ClassworkSchema );

module.exports = {
  User : User ,
  Classwork : Classwork 
}

in controller.js

const {User} = require('../models/certification');
const {Classwork } = require('../models/certification');

after require models you can use new Crosswork like this:

note : Classwork with uppercase character

let new_classwork = new Classwork()