Array of Arrays

controllers.application.js

import Ember from 'ember';

let Container = Ember.Object.extend({
  init() {
    this.set('items', []);
  },
  comp2: Ember.computed('items.@each.j', function() {
    console.log('2deep');
    //console.log(this.items.mapBy('j'));
    return Math.random();
  }),
  obs: Ember.observer('items.@each.j', function() {
    //console.log(this.items.mapBy('i'));
    console.log('observed2');
    this.notifyPropertyChange('obs');
  }),
});


let Item = Ember.Object.extend({
  j: Ember.observer('i', function() {
    console.log('j');
    //console.log(this.i);
    this.notifyPropertyChange('j');
    return Math.random();
  }),
});

let counter = 0;
export default Ember.Controller.extend({
  init() {
    let result = [];
    let last = null, lastRow = null;
    for (let i=0; i<5; i++) {
      let row = Container.create();
      for (let j=0; j<4; j++) {
        let item = last = Item.create({i: j});
        row.items.pushObject(item);
      }
      lastRow = row;
      result.push(row);
    }
    
    this.set('a', result);
    this.set('last', last);
    this.set('lastRow', lastRow);
  },
  
  obs: Ember.observer('a.@each.compx', function() {
    //console.log(this.a.mapBy('comp'));
    console.log('observed');
  }),
  
  comp: Ember.computed('a.@each.obs', function() {
    console.log('comp');
    //console.log(this.a.mapBy('comp2'));
    //console.log(this.a.mapBy('items').map(x => x.mapBy('j')));
    //console.log(this.a);
    return Math.random();
  }),
  
  actions: {
    increment() {
      //this.last.notifyPropertyChange('i');
      this.lastRow.items.invoke('notifyPropertyChange', 'i');
      //this.last.set('i', counter++);
      //this.set('i', counter++);
    },
    
    read() {
      //console.log(this.last.i);
      //console.log(this.a.mapBy('comp'));
      //console.log(this.lastRow.items.mapBy('i'));
    },
  },
});

templates.application.hbs

<h1>Listener on array of arrays</h1>
<br>
<br>
{{comp}}
<button {{action 'increment'}}>Increment</button>
<button {{action 'read'}}>Read</button>

{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}