Get random item from Firebase

Question

I searched for it, but all the answers are pretty old so maybe there is a better way. I\'m trying to get a random item from a Firebase DB which looks like this:

Answer 1

If you know how many users there are, you can do this:

const numberOfUsers = 15;
const randomIndex = Math.floor(Math.random() * numberOfUsers);

var ref = firebase.database().ref('companies/01/users');

ref.limitToFirst(randomIndex).limitToLast(1).once('value').then(snapshot =>
{
    var user = snapshot.val();
    // do something with the user data
});

However, if you don't know how many children there are (or have a children list stored somewhere else), there is no direct way to solve this problem without first receiving all children in the tree. See In Firebase, is there a way to get the number of children of a node without loading all the node data? for more info.