Access controller scope from directive

I've created a simple directive that displays sort column headers for a <table> I'm creating.

ngGrid.directive("sortColumn", function() {
    return {
        restrict: "E",
        replace: true,
        transclude: true,
        scope: {
            sortby: "@",
            onsort: "="
        },
        template: "<span><a href='#' ng-click='sort()' ng-transclude></a></span>",
        link: function(scope, element, attrs) {
            scope.sort = function () {

                // I want to call CONTROLLER.onSort here, but how do I access the controller scope?...
                scope.controllerOnSort(scope.sortby);
            };
        }
    };
});

Here's an example of some table headers being created:

<table id="mainGrid" ng-controller="GridCtrl>
<thead>
    <tr>
        <th><sort-column sortby="Name">Name</sort-column></th>
        <th><sort-column sortby="DateCreated">Date Created</sort-column></th>
        <th>Hi</th>
    </tr>
</thead>

So when the sort column is clicked I want to fire the onControllerSort function on my grid controller.. but I'm stuck! So far the only way I've been able to do this is for each <sort-column>, add attributes for the "onSort" and reference those in the directive:

<sort-column onSort="controllerOnSort" sortby="Name">Name</sort-column>

But that's not very nice since I ALWAYS want to call controllerOnSort, so plumbing it in for every directive is a bit ugly. How can I do this within the directive without requiring unnecesary markup in my HTML? Both the directive and controller are defined within the same module if that helps.

Solution

Create a second directive as a wrapper:

ngGrid.directive("columnwrapper", function() {
  return {
    restrict: "E",
    scope: {
      onsort: '='
    }
  };
});

Then you can just reference the function to call once in the outer directive:

<columnwrapper onsort="controllerOnSort">
  <sort-column sortby="Name">Name</sort-column>
  <sort-column sortby="DateCreated">Date Created</sort-column>
</columnwrapper>

In the "sortColumn" directive you can then call that referenced function by calling

scope.$parent.onsort();

See this fiddle for a working example: http://jsfiddle.net/wZrjQ/1/

Of course if you don't care about having hardcoded dependencies, you could also stay with one directive and just call the function on the parent scope (that would then be the controller in question) through

scope.$parent.controllerOnSort():

I have another fiddle showing this: http://jsfiddle.net/wZrjQ/2

This solution would have the same effect (with the same criticism in regard to hard-coupling) as the solution in the other answer (https://stackoverflow.com/a/19385937/2572897) but is at least somewhat easier than that solution. If you couple hard anyway, i don't think there is a point in referencing the controller as it would most likely be available at $scope.$parent all the time (but beware of other elements setting up a scope).

I would go for the first solution, though. It adds some little markup but solves the problem and maintains a clean separation. Also you could be sure that $scope.$parent matches the outer directive if you use the second directive as a direct wrapper.