Does it make sense to use ObjectController and ArrayController together? - ember.js

Question

I have a list of object, stored in an arrayController and rendered on the view using the #each macro
{{#each item in controller}}
{{view App.ItemView}}
{{/each}}
Each item view has class name binding that depends on the user action. For exemple :
App.ItemView = Ember.View.extend {
classNameBindings: ['isSelected:selected']
}
isSelecteddepends on the state of each Item : I have to store the selected item somewhere, and compare it to the new selected item if a click event is triggered.
The question is: where should I compute this isSelectedproperty ? In the itemsController ? In an itemController? Directly in each itemView ?

Answer 1

To me, it does make sense to put it into the view as, moreover, it is really a display concern.
You've got an example here: http://jsfiddle.net/MikeAski/r6xcA/
Handlebars:
<script type="text/x-handlebars" data-template-name="items">
{{#each item in controller}}
{{view App.ItemView contentBinding="item"}}
{{/each}}
</script>
<script type="text/x-handlebars" data-template-name="item">
Item: {{item.label}}
</script>
​JavaScript:
App.ItemsController = Ember.ArrayController.extend({
selected: null
});
App.ItemsView = Ember.View.extend({
templateName: 'items'
});
App.ItemView = Ember.View.extend({
templateName: 'item',
classNameBindings: ['isSelected:selected'],
isSelected: function() {
var item = this.get('content'),
selected = this.getPath('controller.selected');
return item === selected;
}.property('item', 'controller.selected'),
click: function() {
var controller = this.get('controller'),
item = this.get('content');
controller.set('selected', item);
}
});
App.ItemsView.create({
controller: App.ItemsController.create({
content: [{ label: 'My first item' },
{ label: 'My second item' },
{ label: 'My third item' }]
})
}).append();
​

Answer 2

It sounds like you need two things - an isSelected property on the item itself (the model) which answers the question, "Is this item selected?", and a selectedItem property on the itemsController, which answers the question, "Which item is selected?" The property on the model is just a get/set; you could compute itemsController.selectedItem by filtering the list of items for one where isSelected is true, or you could set it explicitly with some code to un-select previously unselected items.