Как перебрать список учеников, которые относятся к этому классу?

Question

Как мне перечислить только учеников, которые относятся к классу?

**Student MongoDB**
id: ObjectId('5cafc39681d41e11ecccd042')
classroom:
  Objectid:('5cafb1d9a36c8123f86b8e30')
fullName:"Student Jim"
__v:0

**Classroom MongoDB**
_id: ObjectId:('5cafb1d9a36c8123f86b8e30')
author: Objectid:('5ca405020a1fef3ed0a3dcb8')
createdAt:2019-04-11T21:30:01.004+00:00
classroomname:"Classroom 2"
__v:0

Теперь я попытался выполнить итерацию, поэтому я могу перечислить только учеников, принадлежащих к классу, на который я нажал, который открывается в http://localhost:8080/classroom/students/5cafb1d9a36c8123f86b8e30, который является идентификатором класса.

Вот как я пытался повторить:

    extends layout

block content
    for classroom in classrooms && student in students
        if student.classroom.id == classroom.id
            p= student.fullName

Я не уверен, что я на правильном пути, если я - я пропускаю только часть итерации. Спасибо за помощь.

ОБНОВЛЕНИЕ С БОЛЕЕ КОДОМ

**Classroom.controller.js**


   const express = require('express');
var router = express.Router();
var bodyParser = require('body-parser')
const mongoose = require('mongoose');
const passport = require('passport');
const ObjectId = mongoose.Types.ObjectId;

const Student = require('../models/student');
const Classroom = require('../models/classroom');

const passportConfig = require('../config/passport');


const app = express();

// Get classroom add page
router.get('/',passportConfig.isAuthenticated,(req, res) => {
    res.render('classroom');

});


// Insert new classroom
router.post('/',(req, res) => {
        InsertRecord(req, res);

});

// Update the classroom name
router.post('/update', (req, res) => {
    updateRecord(req, res);
});


function updateRecord(req,res){
    Classroom.findOneAndUpdate({ _id: req.body._id}, req.body, {new: true}, (err,doc)=> {
        if (!err) { res.redirect('./names');}
        else {
            if (err.name == 'ValidationError'){
                handleValidationError(err, req.body);
                res.render('update', {
                    classroom: req.body
                });
            }
            else 
                console.log('Error during update:' +err);
        }
    });
}

// Add new classroom to the database

function InsertRecord(req, res){
    var classroom = new Classroom();
    classroom.classroomname = req.body.classroomname;
    classroom.author.id = req.user._id,
    classroom.save((err, doc) => {
        if (!err)
            res.redirect('classroom/names');
        else {
            if (err.name == 'ValidationError') {
                handleValidationError(err, req.body);
                res.render('classroom/names', {
                    viewTitle: 'Insert Classroom',
                    classroom: req.body
                });
            }
            else
                console.log('Error during record insertion:' + err);
        }
    });

}





// List all the classrooms that belongs to the logged user

 router.get('/names',passportConfig.isAuthenticated, (req, res) => {
    Classroom.find((err, docs) => {
        if (!err) {
            res.render('names', {
                classrooms:docs

            });
        }
        else {
            console.log('Error in retrieving students: '+ err);
        }
    });
});



router.get("/students/:classroomid", async (req, res) => {
  const classId = mongoose.Types.ObjectId(req.params.classroomid)
  const students = await Student.find({
    classroom: classId
  }, {
    fullName: 1
  })
  res.render('studentsinclass', {
    students: students
  })
})


// Update classroom name by ID
router.get('/update/:id',passportConfig.isAuthenticated,(req, res) => {
    Classroom.findById(req.params.id, (err, docs) => {
        if (!err) {
            res.render('update', {
                viewTitle: 'Update',
                classrooms: docs
            });
        }

    });

});

// delete Classroom by ID

router.get('/delete/:id',passportConfig.isAuthenticated,(req, res) => {
    Classroom.findByIdAndRemove(req.params.id, (err, docs) => {
        if (!err) {
            res.redirect('/classroom/names');
        }
        else {console.log('Error in classroom deletion:' +err);}

    });

});


module.exports = router;

**Classroom Schema**
const mongoose = require('mongoose');


const classroomSchema = new mongoose.Schema({
  classroomname:  {
    type: String
  },
  createdAt: { type: Date, default: Date.now },
  author: {
    id: {
        type: mongoose.Schema.Types.ObjectId, 
        ref: "User",

    },
   },
  students: {
    id : {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Student"
    }
  }

});

const Classroom = mongoose.model('Classroom', classroomSchema);

module.exports = Classroom;


**Students.controller.js**
const express = require('express');
var router = express.Router();
var bodyParser = require('body-parser')
const mongoose = require('mongoose');
const passport = require('passport');

const Student = require('../models/student');
const Classroom = require('../models/classroom');
const passportConfig = require('../config/passport');

const app = express();


// router.get('/',passportConfig.isAuthenticated,(req, res) => {
//  res.render('students');

// });
router.get('/',passportConfig.isAuthenticated,(req, res) => {
    Classroom.find((err, docs) => {
        if (!err) {
            res.render('students', {
                classrooms: docs
            });
        }

    });

});




router.post('/',(req, res) => {
    InsertRecord(req, res);

});

function InsertRecord(req, res){
    var student = new Student();
    student.fullName = req.body.fullname;
    student.classroom.id = req.body.studentclassroom;
    student.save((err, doc) => {
        if (!err)
            res.redirect('students/list');
        else {
            console.log(' Error during insertion: '+ err);
        }
    });

}



router.get('/list',passportConfig.isAuthenticated, (req, res) => {
    Student.find((err, docs) => {
        if (!err) {
            res.render('list', {
                list:docs

            });
        }
        else {
            console.log('Error in retrieving students: '+ err);
        }
    });
});





module.exports = router;

**Students schema**
const mongoose = require('mongoose');


const studentSchema = new mongoose.Schema({
    fullName: {
        type: String
    },
    classroom: {
                name: {
                        type: String
                        },
                id: {
                        type: mongoose.Schema.Types.ObjectId, 
                        ref: "classroom",
                    }
                },

});

const Student = mongoose.model('Student', studentSchema);

module.exports = Student;

Answer 1

Если вы используете express и pug с mongoose, тогда передайте требуемый результат напрямую вместо метода поиска двух циклов

import mongoose from 'mongoose'
.....
app.get("/classroom/students/:classRoomId", async (req, res) => {
  const classId = mongoose.Types.ObjectId(req.params.classRoomId)
  const students = await Student.find({
    classroom: classId
  }, {
    fullName: 1
  })
  res.render('index', {
    students: students
  })
})

index.pug

                    extends layout
block content
  for student in students
    p = student.fullName

Здесь вы можете использовать непосредственно переменную студента.

Answer 2

С помощью Ашока и некоторых небольших модификаций я заставил его работать.Вот рабочий код.

  app.get("/classroom/students/:id", async (req, res) => {
  const classId = mongoose.Types.ObjectId(req.params.id)
  // console.log(classId);
  const students = await Student.find({
    'classroom.id': classId
  })
  res.render('studentsinclass',{
    students:students})
})