Array deep watch in angular view (html) - angularjs

Question

This is my view (html):
<my-directive collection="currentData"></my-directive>
and this is the data structure:
$scope.currentData = [...
{
"name": "lala Page",
"icon": "icon-docs",
"sub_data": [
{
"name": "1-article",
"href": "/1-article",
"icon": "fa fa-pencil"
},
{
"name": "2-article",
"href": "/2-article",
"icon": "fa fa-pencil"
},
{
"name": "3-article",
"href": "/3-article",
"icon": "fa fa-pencil"
}
...
]...
}]
Inside my-directive there are bind-once elements (on sub_data).
If the all array change - the view is changed,
but when I change the sub_data, the view don't updated.
Any idea, how to make the collection be affected by a changes in sub_data?
(I do want to use as less watchers as possible)
Edit
Adding the my-directive code:
angular.module('my_module',[]).directive('myDirective', function(){
return {
scope:{
collection: '='
},
replace: true,
template: ['<li my-directive-item ng-repeat="item in collection" raw-model="{{::item}}">',
'</li>'].join('')
};
});
I don't have a watch on collection, only the code above. I meant angular doesn't update the collection binding unless I change the array itself, and I want it to update the view when i change a sub property of an item in the collection.

Answer 1

Ok, I solved it. I'm not proud of the solution but it works:
Inside the controller:
$scope.updateArray = function() {
...
// Do stuff with tempData
...
// Trick for updating the view - because of the bind-once sub items
$scope.currentData = [];
$timeout(function(){
$scope.currentData = tempData;
}, 0);
};