Promise.all with Firebase DataSnapshot.forEach

Question

I have a couple of HTML select\'s (dropdowns) that are populated from a Firebase node called \"states\" (see image below). Upon choosing a city, the below function fires an

Answer 1

You have to execute the Promise.all after you filled the array with promises, i.e. inside the then callback:

function loadMeetings(city,state) {
    //$('#meetingsTable').empty();
    return ref.child('states').child(state).child(city).once('value').then(function(snapshot) {
        var reads = [];
//      ^^^^^^^^^^^^^^
        snapshot.forEach(function(childSnapshot) {
            var id = childSnapshot.key;
            var promise = ref.child('meetings').child(id).once('value').then(function(snap) {
                // The Promise was fulfilled.
            }, function(error) {
                // The Promise was rejected.
                console.error(error);
            });
            reads.push(promise);
        });
        return Promise.all(reads);
//      ^^^^^^^^^^^^^^^^^
    }, function(error) {
        // The Promise was rejected.
        console.error(error);
    }).then(function(values) { 
        console.log(values); // [snap, snap, snap] 
    });
}