Firestore: How to get random documents in a collection

Question

It is crucial for my application to be able to select multiple documents at random from a collection in firebase.

Since there is no native function built in to Fireb

Answer 1

Posting this to help anyone that has this problem in the future.

If you are using Auto IDs you can generate a new Auto ID and query for the closest Auto ID as mentioned in Dan McGrath's Answer.

I recently created a random quote api and needed to get random quotes from a firestore collection.
This is how I solved that problem:

var db = admin.firestore();
var quotes = db.collection("quotes");

var key = quotes.doc().id;

quotes.where(admin.firestore.FieldPath.documentId(), '>=', key).limit(1).get()
.then(snapshot => {
    if(snapshot.size > 0) {
        snapshot.forEach(doc => {
            console.log(doc.id, '=>', doc.data());
        });
    }
    else {
        var quote = quotes.where(admin.firestore.FieldPath.documentId(), '<', key).limit(1).get()
        .then(snapshot => {
            snapshot.forEach(doc => {
                console.log(doc.id, '=>', doc.data());
            });
        })
        .catch(err => {
            console.log('Error getting documents', err);
        });
    }
})
.catch(err => {
    console.log('Error getting documents', err);
});

The key to the query is this:

.where(admin.firestore.FieldPath.documentId(), '>', key)

And calling it again with the operation reversed if no documents are found.

I hope this helps!
If interested, you can find this specific part of my API on GitHub