MongoDB Server-side CSV formatting

csv.js

db.system.js.save({
    _id: "csv",
    value: function(doc, fields) {
        var getValue = function(doc, field) {
            var tree = field.split('.');
            var value = doc;
            tree.forEach(function(key) {
                value = value[key];
            })
            return value;
        };
        var str = "\"" + doc._id + "\"";
        fields.forEach(function(field) {
            str = str + ",\"" + getValue(doc, field) + "\"";
        })
        return str;
    }
});

db.loadServerScripts();

var fields = ['email', 'displayName', 'username', 'geoCode.ip', 'geoCode.hostname'];

db.getCollection('Customer').find({"geoCode.hostname":/tor/}).forEach(function(doc) {
    print(csv(doc, fields))
})