Derived properties don't listen to change events from collections

Simplified example:

var Model = require('ampersand-model');
var Collection = require('ampersand-collection');

var Room = Model.extend({
  props: {
    size: ['number', true, 10],
  },
});

var Rooms = Collection.extend({
  model: Room,
});

var House = Model.extend({
  collections: {
    rooms: Rooms,
  },

  derived: {
    totalArea: {
      deps: ['rooms'],
      fn: function() {
        return this.rooms.reduce(function(a, b) {
          return a + b.size;
        }, 0);
      }
    }
  },
});

var house = new House({
  rooms: [{size: 12}]
});

console.log(house.totalArea); // => 12
house.rooms.at(0).size = 15;
console.log(house.totalArea); // => 12

Seems like this should work?

[tnguyen14]

Has there been any progress/ fix for this issue?

[jdiaz5513]

It’s a tricky problem to solve. I use a mixin to deal with this for now…

https://gist.github.com/jdiaz5513/6716e23c4995711db020

Could publish this mixin if it proves to be useful to anyone else.