Associate the callback function with a directive that does not have an isolated scope

Question

Associate the callback function with a directive that does not have an isolated scope

Ensuring the correct context when binding a callback function to a directive is crucial. When working with an isolated scope, this task is easily accomplished.

<bar-foo callback="mycontroller.callback()"></bar-foo>

The directive code:

 ...
 scope:{
     callback: '&'
 },
 ...

If there is no isolated scope, I extract the callback from the $attrs attribute:

$scope.callback = $parse($attrs.callback)($scope);

However, in such cases I cannot simply use:

<bar-foo callback="mycontroller.callback()"></bar-foo>

This would lead to executing the callback directly. What would be the most recommended solution for this issue?

DEMO

javascript angularjs angularjs-directive

Answer 1

Answer №1

To start, create a new function within your controller that explicitly defines the value of this inside it:

this.exportableCallback = this.callback.bind(this);

The next step is to assign it as an attribute in your code:

<hello-world callback="mycontroller.exportableCallback"></hello-world>

Remember not to call the function like you did with the isolated scope.

You can check out a working example in this Fiddle link.

Another option, if you remove this.callback from your controller, is to define the exportable callback function like this:

this.exportableCallback = function() {
  console.log(this.test);
}.bind(this);

If you need to pass arguments to this function, simply use:

this.exportableCallback = function() {
  console.log(arguments);
}.bind(this);

Answer 2

To start, create a new function within your controller that explicitly defines the value of this inside it:

this.exportableCallback = this.callback.bind(this);

The next step is to assign it as an attribute in your code:

<hello-world callback="mycontroller.exportableCallback"></hello-world>

Remember not to call the function like you did with the isolated scope.

You can check out a working example in this Fiddle link.

Another option, if you remove this.callback from your controller, is to define the exportable callback function like this:

this.exportableCallback = function() {
  console.log(this.test);
}.bind(this);

If you need to pass arguments to this function, simply use:

this.exportableCallback = function() {
  console.log(arguments);
}.bind(this);

Answer 3

Answer №2

Is it really as simple as just defining and using your directive without any isolation?

    .directive('greeting', function () {
    return {
        restrict: 'E',
        template: '<button ng-click="myCtrl.sayHello()">No isolation needed</button>',
    }
});

Can you really just include your directive like this?

<greeting></greeting>

Or is there more to it that I'm not seeing? Maybe specifying the controller with the require attribute is a good idea after all.

Answer 4

Is it really as simple as just defining and using your directive without any isolation?

    .directive('greeting', function () {
    return {
        restrict: 'E',
        template: '<button ng-click="myCtrl.sayHello()">No isolation needed</button>',
    }
});

Can you really just include your directive like this?

<greeting></greeting>

Or is there more to it that I'm not seeing? Maybe specifying the controller with the require attribute is a good idea after all.

Answer 5

Answer №3

If you have a directive without a scope, simply call mycontroller.callback() in the directive's template.

.directive('helloWorld', function () {
    return {
        restrict: 'E',
        scope: false,
        //Use THIS
        template: '<button ng-click="mycontroller.callback()">Not isolated</button>',
        //NOT this                  
        //template: '<button ng-click="callback()">Not isolated</button>',
        controller: function ($attrs, $scope, $parse) {
              //$scope.callback = $parse($attrs.callback)($scope);
        }
    }
});

Since the directive doesn't have its own scope, the template can directly access the controller instantiated with

ng-controller="MyCtrl as mycontroller"

.

What if you need to reuse the directive?

In such instances, attach a click handler to the element.

.directive('helloWorld', function () {
    return {
        restrict: 'E',
        scope: false,
        template: '<button>Not isolated</button>',
        link: function (scope, elem, attrs) {
             elem.on("click", function(e) {
                 scope.$eval(attrs.callback, {$event: e});
             });
        }
    }
});

When the directive's element is clicked, the Angular expression specified by the callback attribute will be evaluated with access to the event object as $event.

For more details on $event, refer to AngularJS Developer Guide -- $event.

Answer 6

If you have a directive without a scope, simply call mycontroller.callback() in the directive's template.

.directive('helloWorld', function () {
    return {
        restrict: 'E',
        scope: false,
        //Use THIS
        template: '<button ng-click="mycontroller.callback()">Not isolated</button>',
        //NOT this                  
        //template: '<button ng-click="callback()">Not isolated</button>',
        controller: function ($attrs, $scope, $parse) {
              //$scope.callback = $parse($attrs.callback)($scope);
        }
    }
});

Since the directive doesn't have its own scope, the template can directly access the controller instantiated with

ng-controller="MyCtrl as mycontroller"

.

What if you need to reuse the directive?

In such instances, attach a click handler to the element.

.directive('helloWorld', function () {
    return {
        restrict: 'E',
        scope: false,
        template: '<button>Not isolated</button>',
        link: function (scope, elem, attrs) {
             elem.on("click", function(e) {
                 scope.$eval(attrs.callback, {$event: e});
             });
        }
    }
});

When the directive's element is clicked, the Angular expression specified by the callback attribute will be evaluated with access to the event object as $event.

For more details on $event, refer to AngularJS Developer Guide -- $event.

Associate the callback function with a directive that does not have an isolated scope

Answer №1

Answer №2

Answer №3

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