Invoking a function within the directive's controller

How can I access and call the method defined within the directive controller externally?

<div ng-controller="MyCtrl">
    <map></map>
    <button ng-click="updateMap()">call updateMap()</button>
</div>

app.directive('map', function() {
    return {
        restrict: 'E',
        replace: true,
        template: '<div></div>',
        controller: function(){
           $scope.updateMap = function(){
              //ajax call here.
           }
        },
        link: function($scope, element, attrs) {
            $scope.updateMap();
            //do some dom transformation
        }
    }
});

In my view, I am looking to invoke the updateMap() method. How would I go about doing this?

Answer №1

By exposing the function on the controller rather than the scope, you can make the controller accessible on the parent scope like this:

    controller: function($scope, $element, $attrs){
       // Make sure to add the controller to the parent scope when creating a new scope within the directive
       $scope.$parent[$attrs["name"]]=this;   

       this.updateMap = function(){
          //perform ajax call here.
       }
    },

Now in the main controller, you can easily access the controller:

<button ng-click="myMap.updateMap()">call updateMap()</button>

Just like how ng-model exposes its controller. Consider the controller as an API for your directive.

Answer №2

It is not recommended to directly access a function from the controller in this way. However, you can bind the updateMap function to $rootScope so that it can be accessed globally while still passing the current scope as a parameter to it.

For example:

$rootScope.updateMap = function($scope) {
  // use the scope to perform manipulations
}

<div ng-controller="MyCtrl">
 <map></map>
 <button ng-click="updateMap(this)">call updateMap()</button>
</div>

By passing 'this' in the updateMap function, it will reference the scope in which the element is located. In the given scenario, 'this' will point to MyCtrl's $scope.

Answer №3

If you're looking for suggestions, I have two options in mind. Let's start with a simple solution using events:

<div ng-controller="MyCtrl">
    <map></map>
    <button ng-click="updateMap()">call updateMap()</button>
</div>

app.directive('map', function() {
    return {
        restrict: 'E',
        replace: true,
        template: '<div></div>',
        controller: function(){
           $scope.updateMap = function(){
              //ajax call here.
           }
        },
        link: function($scope, element, attrs) {
            $scope.$on('my.update.map.event', $scope.updateMap);
        }
    }
});

app.controller('MyCtrl', function ($scope) {
    $scope.updateMap = function () {
        $scope.$broadcast('my.update.map.event');
    };
});

This method is not bad at all. It ensures that the root scope isn't affected (@Krishna's suggestion) and your map directive doesn't clutter your controller's scope (@Chandermani's advice).

Another choice, if you prefer to avoid using events, is to utilize the controllerAs syntax to expose your map directive's controller.

<div ng-controller="MyCtrl">
    <map controller="mapController"></map>
    <button ng-click="mapController.updateMap()">call updateMap()</button>
</div>

app.directive('map', function() {
    return {
        restrict: 'E',
        replace: true,
        scope: {
            'controller': '=?'
        },
        template: '<div></div>',
        controllerAs: 'controller',
        controller: function(){
           this.updateMap = function(){
              //ajax call here.
           }
        },
        link: function($scope, element, attrs, ctrl) {
            ctrl.updateMap();
        }
    }
});

This approach is similar to @Chandermani's suggestion, but it clearly defines the relationship between your controller and your directive. By using the view, you can see that the map directive is exposing its controller as mapController within MyCtrl's scope.

(I came across this concept here).

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