exercice3.js

'use strict'
var MongoClient = require('mongodb').MongoClient;
var url = 'mongodb://localhost:27020';

const findCourse = async (db, courseName) => {
  const course = await db.collection('courses').findOne({name: courseName});
  if (!course) {
    throw new Error('Course not found');
  }
  return course;
}

const getNote = (db, code, student) => {
  return db.collection('notes').findOne({
    code,
    student
  });
}

const getStudentList = (db, program, program_year, year) => {
  const pipeline = [
    {$unwind: '$programs'},
    {$unwind: '$programs.inscription'},
    {$match: {
        'programs.inscription.year': parseInt(year),
        'programs.code': program,
        'programs.inscription.program_year': program_year
      }
    },
    {$sort: {name: 1}}
  ];
  return db.collection('students').aggregate(pipeline).toArray();
}

const main = async () => {
  const year = process.argv[3];
  const courseName = process.argv[2];
  console.log('Looking for', courseName, 'on', year);

  let client;
  try {
    client = await MongoClient.connect(url);
    console.log("Connecté");

    const db = client.db('lpdw-university');

    const course = await findCourse(db, courseName);
    const students = await getStudentList(db, course.program, course.year, year);

    const promises = students.map(s => getNote(db, course.code, s.code));
    const notes = await Promise.all(promises);

    students.map((s, index) => {
      console.log(s.code, s.name, '\t', notes[index].score);
    })

    await client.close();
  }
  catch(err) {
    console.log(err);
    process.exit(1);
  }
};

main();