nutrient-total-helper

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  list: [],
  
  actions: {
  	add() {
  		this.get('list').pushObject({
      	ingredient: {
        	name: 'Potato',
          group: 'Veggies',
          nutrients: [{
          	name: 'kcal',
            nutritionalValue: 87
          }, {
          	name: 'kJ',
            nutritionalValue: 42
          }]
        },
        weight: 42
      });
      
      this.notifyPropertyChange('list');
		}
	}
});

helpers.nutrient-total.js

import Ember from 'ember';
const {get} = Ember;

export function nutrientTotal([list, unit]) {
  let total = 0;

	list.forEach(item => {
    let weight = get(item, 'weight');

    get(get(item, 'ingredient'), 'nutrients').forEach(nutrient => {
      if (get(nutrient, 'name') === unit) {
        total += weight * get(nutrient, 'nutritionalValue');
      }
    });
  });

  return total;
}

export default Ember.Helper.helper(nutrientTotal);

templates.application.hbs

<table style="width:100%">
  <tr>
    <th>Group</th>
    <th>Name</th>
    <th>Weight</th>
  </tr>
  {{#each list as |item|}}
    <tr>
      <td>{{item.ingredient.group}}</td>
      <td>{{item.ingredient.name}}</td>
      <td>{{item.weight}}g</td>
    </tr>
  {{/each}}
</table>

<br>

<button {{action "add"}}>Add</button>

<br>
<br>

{{nutrient-total list "kcal"}}

twiddle.json

{
  "version": "0.11.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.11.0",
    "ember-data": "2.11.0",
    "ember-template-compiler": "2.11.0",
    "ember-testing": "2.11.0"
  },
  "addons": {}
}