Question

I want to create an array of ratings, and inside this array I want somehow associate rating and date this rating was checked.
right now I have this solution:

> db.foo.find().pretty()
{
    "_id" : ObjectId("511a604f546e6b3019d5e673"),
    "ratings" : [
        {
            "rating" : 3,
            "date" : ISODate("2013-02-12T15:31:27.950Z")
        },
        {
            "rating" : 5,
            "date" : ISODate("2013-02-12T15:34:12.072Z")
        },
        {
            "rating" : 3,
            "date" : ISODate("2013-02-12T15:34:33.009Z")
        }
    ]
}

With this “schema” I see the only one BIG issue, I think it’s little to complicated to sort documents by date, if I’m wrong, please correct me. How would you design it?

Answer 1

Store the ratings in a separate “ratings” collection.

This strategy adds the minor complication of needing two queries to display a “foo” and its ratings (one query for each collection) but has the advantage of flexibility and scalability.

See also this advice from 10gen: Storing Comments.