Angular: calling controller function inside a directive link function using &

We're running into a problem trying to call a function passed into a directive using the ampersand '&' in our directive's link function.

It seems the function is called on the controller but no arguments are passed in the call. All the examples we have seen involve passing through by creating a call in template. Is there a way to call a function on your directive from its template, then do something in the directive that calls the controller function passed into it?

Are you passing the arguments inside {}s? E.g., inside the directive's link function, you'll want to call the method like so: scope.someCtrlFn({arg1: someValue});

<div my-directive callback-fn="ctrlFn(arg1)"></div>

app.directive('myDirective', function() {
    return {
        scope: { someCtrlFn: '&callbackFn' },
        link: function(scope, element, attrs) {
            scope.someCtrlFn({arg1: 22});
        },
    }
});

function MyCtrl($scope) {
    $scope.ctrlFn = function(test) {
        console.log(test);
    }
}

Fiddle.

In addition to Mark's answer I'd like to point out that you can spare some letters using the & shorthand. This will assume that the callback-fn referenced in your HTML exists as scope.callbackFn in your scope. Everthing else is still the same, so there are only 2 lines to change. I kept Mark's version as comments, so you should be able to spot the difference easily.

<div my-directive callback-fn="ctrlFn(arg1)"></div>

app.directive('myDirective', function() {
    return {
        scope: { callbackFn: '&' }, //scope: { someCtrlFn: '&callbackFn' },
        link: function(scope, element, attrs) {
            scope.callbackFn({arg1: 22}); //scope.someCtrlFn({arg1: 22});
        },
    }
});

function MyCtrl($scope) {
    $scope.ctrlFn = function(test) {
        console.log(test);
    }
}