Angular invoke controller fn from directive isolated template - angularjs

Question

I want on-click event from directive invoke some function from my controller. But for some reason it doesn't work. I want my datepicker to expand when I event is fired. Could you please help me to investigate what is wrong my in my current build?
app.js
app.directive('myDatepicker', function() {
return {
restrict: 'E',
scope :{
model:'=model',
minDate:'=minDate',
isOpened:'=isOpened',
openFunction: '&'
},
templateUrl: 'templates/datepicker/datepicker.html',
link: function(scope, elm, attrs) {
}
};
});
app.controller('FlightDatePickerController', function ($scope) {
$scope.openFunction = function($event, isDepart) {
$event.preventDefault();
$event.stopPropagation();
$scope.departureOpened = true;
};
};
datepicker.html
<fieldset>
<pre>{{model}}</pre>
<div class='input-group'>
<input type="text" class="form-control" datepicker-popup ng-model="{{model}}" min-date="{{minDate}}" is-open="{{isOpened}}" datepicker-options="dateOptions" ng-required="true" close-text="Close" />
<span ng-click='openFunction({event:event}, {isDepart:isDepart})' class="btn btn-default input-group-addon">
<span class="glyphicon glyphicon-calendar"></span>
</span>
</div>
</fieldset>
index.html
<div ng-controller="FlightDatePickerController">
<div class="col-md-2">
<my-datepicker model="departureDate" minDate="minDateDeparture" isOpened="departureOpened" open-function="openFunction($event, isDepart)"></my-datepicker>
</div>
</div>

Answer 1

You can add a controller attribute to your directive, in order to bind some function to your template.
In your case, you can do :
Directive
app.directive('myDatepicker', function() {
return {
restrict: 'E',
scope :{
model:'=model',
minDate:'=minDate',
isOpened:'=isOpened'
},
templateUrl: 'templates/datepicker/datepicker.html',
controller: 'FlightDatePickerController'
};
});
Datepicker.html
<div ng-controller="FlightDatePickerController">
<div class="col-md-2">
<my-datepicker model="departureDate" minDate="minDateDeparture" isOpened="departureOpened"></my-datepicker>
</div>
</div>

Answer 2

Your overall implementation is correct, but you made couple of mistakes.
ng-click should be like adding parameter in JSON like structure.
ng-click='openFunction({event:$event, isDepart:isDepart})'
& then your directive element should have
open-function="openFunction($event, isDepart)"