javascript - How can I paginate in descending order by child value with firebase?

Question

Let's say I have some data as follows:

{
    "name": "post #1",
    "votes": 100
},
{
    "name": "post #2",
    "votes": 10000
},
{
    "name": "post #3",
    "votes": 750
}

And so on.

The data in firebase is not ordered by votes obviously, it's order by key.

I'd like to be able to paginate this data by the number of votes in descending order.

I think I'd have to do something like:

ref.orderByChild('votes')
    .startAt(someValue)
    .limitToFirst(someOtherValue)
    .once('value', function(snapshot) {
        resolve(snapshot);
    });

Or perhaps, I'd need to use limitToLast, and endAt?

Pagination by key is quite easy, but this one is stumping me.

Update (2017-10-16): Firebase recently announced Firestore - their fully managed NoSQL datastore which should make it easier to do more complex queries. There may still be some use cases where one might use the Realtime database they've always provided. If you're one of those people this question should still apply.

Answer 1

Waitting for answers