gistfile1.txt

var MongoClient = require('mongodb').MongoClient;


MongoClient.connect('mongodb://localhost:27017/school', function(err, db) {
    if(err) throw err;

    function iterate(list, func) {
        'use strict';

        var i, res;

        if ('length' in list && typeof list !== 'function') {
            res = [];
            for (i = 0; i < list.length; i += 1) {
                res.push(func.call(err, list, list[i], i));
            }
        } else {
            res = {};
            for (i in list) {
                if (list.hasOwnProperty(i)) {
                    res[i] = func.call(err, list, list[i], i);
                }
            }
        }
        return res;
    }


    db.collection('students').find().sort([['name', 1], ['scores.score', 1]]).toArray(function(err, docs) {
        if(err) throw err;

        var lowScores = [];

        function minScore(scores) {
            var minScore;
            iterate(scores, function(scores, elem, i) {
                if(elem.type == "homework") {
                    if(!minScore){
                        minScore = elem.score;
                    } else if(minScore > elem.score) {
                        minScore = elem.score;
                    }
                }
            });
            return minScore;
        }

        iterate(docs, function(docs, doc, i ) {
            var obj;

            obj = {
                score: minScore(doc.scores),
                id: doc._id
            }
            lowScores.push(obj);
        });

        iterate(lowScores, function(arr, item, i) {
            var score = item.score;
            var id = item.id;
            console.log(score);
            db.collection('students').update({_id:id}, {$pullAll: {scores: [{type: 'homework', score: score}]}}, function(err, updated) {
                if(err) throw err;
                console.log('successful update' + updated);
            });
        });
    });
});