Question

Counting records in a table is obviously a manual effort until you guys get some of that spiffy new functionality already in the works 😉

However, I’m stuck on even using a manual run with .on(‘value’, …) to fetch a count:

var table = new Firebase('http://beta.firebase.com/user/tablename');
var count = 0;
table.on('child_added', function(snapshot) {
   count++;
   // how do I know if this is the last child? i.e. the count is complete?
});

// when is it okay to use count?

I foresee the same issues with any sort of pagination and I feel like I’m being a bit blockheaded about this. What am I missing?

Is this fundamentally the wrong pattern for, say, getting the number of messages a user has in his/her queue?

Answer 1

With “child_added” there is no way to know when you’ve received the “last” item. If you’re looking to count all of the children that existed at a particular point in time, I’d suggest using the “value” event as follows:

var table = new Firebase('http://beta.firebase.com/user/tablename');

table.on('value', function(snapshot) {
   var count = 0;
   snapshot.forEach(function() {
       count++;
   });
   //count is now safe to use.
});