Get documents with tags in list, ordered by total number of matches

Question

Given the following MongoDB collection of documents :

{
 title : \'shirt one\'
 tags : [
  \'shirt\',
  \'cotton\',
  \'t-shirt\',
  \'black\'
 ]
},
{
 title         


        

Answer 1

I'll second @Bryan in saying that MapReduce is the only possible way at the moment (and it's far from perfect). But, in case you desperately need it, here you go :-)

    var m = function() {
        var searchTerms = ['shirt', 'cotton', 'black'];
        var me = this;
        this.tags.forEach(function(t) {
            searchTerms.forEach(function(st) {
                if(t == st) {
                    emit(me._id, {matches : 1});
                }
            })
        })
    };

    var r = function(k, vals) {
        var result = {matches : 0};
        vals.forEach(function(v) {
            result.matches += v.matches;
        })
        return result;
    };

    db.shirts.mapReduce(m, r, {out: 'found01'});

    db.found01.find();