如何使用 nodejs、expressjs 将教师 id /name 推送到 mongodb 中的 studentSchema

Question

I want to add favorite teachers id to student schema from list of teachers. So when the student clicks the "add favorite teacher " button, that particular teacher id will save in the student schema.

Here is my student schema

    const mongoose = require ('mongoose')
    const studentSchema=new mongoose.Schema({
    name:{type:String,required:true}, 
    email:{type:String,required:true}, 
    phone:{type:String,required:true}, 
    password:{type:String,required:true},
    teacher : [{type : mongoose.Schema.Types.ObjectID , ref:'teachers'}],
       
})

const studentModel = mongoose.model('students',studentSchema)
module.exports=studentModel

Here is my teacher Schema

const mongoose = require ('mongoose')

    const teacherSchema=new mongoose.Schema({
        name:{type:String,required:true}, 
        email:{type:String,required:true}, 
        phone:{type:String,required:true}, 
        password:{type:String,required:true}, 
    })
    
    const teacherModel = mongoose.model('teachers',teacherSchema)
    module.exports=teacherModel

So what will be the backend route code to push the teacher id to Student schemas?

Answer 1

It looks like your student schema contains an instance of your teacher schema, not just the teacherID. If your request will contain the studentID in params, and teacherID in its body, I would do something like the following.

I'd first create two middleware functions - one to ensure your returned studentID is valid. Here the studentID is returned in the params via req.params.id .

import { studentModel } from "./models/student.js";


// middleware - check that student id exists
async function checkStudentIdExists(req, res, next) {
  let item;
  try {
    item = await studentModel.findById(req.params.id);
    if (item == null) {
      return res.status(404).json({ message: "cannot find student by given id" });
    }
  } catch (err) {
    return res.status(500).json({ message: err.message });
  }
  res.student = item;
  next();
}

and the second to check that the chosen teacherID is valid. Here the teacherID is returned via the body of the request, req.body.id

import { teacherModel } from "./models/teacher.js";

// check that teacher id exists
async function checkTeacherIdExists(req, res, next) {
  let item;
  try {
    const item = await teacherModel.findById(req.body.id);
    if (item == null) {
      return res.status(404).json({ message: "cannot find teacher by given id" });
    }
  } catch (err) {
    return res.status(500).json({ message: err.message });
  }
  res.teacher = item;
  next();
}

In constructing the required route, use both middleware in a route, like this:

router.patch("/student/favoredTeacher/:id", checkStudentIdExists, checkTeacherIdExists, async (req, res) => {
  try { 
    await res.student.updateOne({teacher: res.teacher})
  } catch (err) {
    res.status(500).json(err.message);
  }
});