Distinct node js MongoDB case insensitive

Question

I am using distinct in Mongo to return some values in the Jquery Autocomplete like this:

function Reg(title)
    {
        this.title= title;
    }

exports.find = function(req, res) {
var b=req.params.search;
var query = new Array();
var cadsrch = b.split(' ');
var l = cadsrch.length;
var i = 0;
        for (i = 0; i < l; i++) {
            if(cadsrch[i]!=''){
              query[i]=new RegExp('^'+cadsrch[i], 'i');
            }
        }

var data=new Array();
        db.collection('publication', function(err, collection) {
                collection.distinct('title',{content:{'$all':query}},{'$or':[{type:'an'},{type:'pub'}]},
                  function(err, items) {
                         var l=items.length,i=0;
                         for (i=0;i<l;i++){
                            data[i]=new Reg(items[i]);
                         }
                         res.jsonp(data);
                         }
                )
        });
};

The problem is that the columns 'title' is working in case sensitive, I mean for example car is different to Car, I don't know if there is a way to avoid this and take Car the same as car

Answer 1

I just saw this question and I know it has been answered however, for future reference, there was, and is, a "$downcase"; it is called $toLower http://docs.mongodb.org/manual/reference/aggregation/toLower/#exp._S_toLower

db.c.aggregate([
    {$group:{_id:{$toLower:'$title'}}}
]);

There is a problem though, you cannot SEARCH by case insenstive until case insensitive indexes are implemented: https://jira.mongodb.org/browse/SERVER-90 . This means currently you would have to searech by case insensitive regex as you do currently.

Answer 2

That is a brilliant case for a "$downcase" operator in MongoDB's aggregation framework; yet, at this time, it does not exist.

The best you can do is store a searchable, downcased version of title for every document. Thus, your schema would look like:

{
  title: "War and Peace",
  searchable_title: "war and peace"
}

Your query logic would downcase the values prior to querying for the searchable title. For scale, stay away from case insensitive regexes, and go with downcased titles.