M101P week 2 solution in node.js

gistfile1.js

'use strict';
/*
 * Homework assignment 2.2 for M101P, using node.js
 *
 * Notes: this only works because the student id
 * increments by 1, and also because each student
 * has more than 1 homework score. If either of
 * those conditions weren't true, this code would
 * be totally wrong (and dangerous!).
 *
 * At least it does things the 'new' way with
 * MongoClient and streams...
 *
 */

var MongoClient = require('mongodb').MongoClient

MongoClient.connect("mongodb://localhost:27017/students", function(err, db) {
  if (err) {
    return console.dir(err);
  }

  var grades = db.collection('grades')
    , stream = grades.find({type: 'homework'}).sort({student_id: 1, score: 1}).stream();

  var next_id = 0;

  stream.on("data", function(item){
    var curr_id = item.student_id;
    if (curr_id == next_id) {
      console.log('removing item with _id ' + item._id.toString());
      grades.remove(item, function(err, result) {
        if (err) {
          return console.dir(err);
        }
      });
      next_id++;
    }
  });

  stream.on("end", function() {
    db.close;
  });
});