I have a cart model then has items in it that looks something like this

```
[
    {
        "item_id": 1,
        "item_name":"Item 1",
        "item_price": 500
    },
    {
        "item_id": 2,
        "item_name": "Item 2",
        "item_price": 230
    },
    {
        "item_id": 3,
        "item_name": "Item 3",
        "item_price": 150
    }
]

```

I need to sum up the `item_price` property to be able to display it and then pass it along to ember data or an ajax call to complete a purchase.

Not sure if I'm just not understanding the agregate data thing with computeds but I am trying with this

```
totalDue: Ember.computed.sum('model.@each.item_price')

```

On the controller but it's returning 0

I am on ember `2.2.0`