angularjs select all checkbox function

I'm fairly new to angular and have a select all checkbox that checks all the boxes through ng-model/ng-checked.

    <th>
        <input type="checkbox" id="selectAll" ng-model="selectAll"/>
    </th>
    <th>
        ${Case Number}
    </th>
    <tr ng-repeat="item in c.onbCase>
        <td><input type="checkbox" name="checkbox" ng-click="checkboxFunc(item)" ng-model="item.checked" ng-checked="selectAll || item.checked"/></td>
        <td></td>
    </tr> 

I also have a function called checkboxFunc that sets item.selected to true if checked and throws the case number into an array:

$scope.onbNum = [];

    $scope.checkboxFunc =  function(item){
        if(item.selected == false) {
            if($scope.onbNum.indexOf(item.number)==-1){
                $scope.onbNum.push(
                    item.number
                )
            }
            item.selected = true;
        } else {
            if($scope.onbNum.indexOf(item.number)!==-1){
                var pos = $scope.onbNum.indexOf(item.number);
                $scope.onbNum.splice(pos,1)
            }
            item.selected = false;
        }
    }

While the Select All checkbox checks all the boxes when clicked upon, how do I fix my function so that all the case numbers get thrown into the array?