This is how you do it:
function groupByFavColors(host){
var conn = new Mongo(host);
var db = conn.getDatabase("DB-NAME");
var res = db.product.aggregate([
{
// unwind the array
$unwind: '$Values.FavColors',
},
{
// group by..
$group: {
_id: '$Values.FavColors',
num_sold: {
$sum: 1
}
}
}
]);
printjson(res);
}
print("usage: groupbyFavColors(string host);")