Differences: Angular ngController vs Controller embedded in Directive

Question

Differences: Angular ngController vs Controller embedded in Directive

I'm interested in exploring the various scenarios where these two methods of creating a controller can be used:

Using ngController:

myApp.controller('myController', ['$scope', function ( $scope ) {

}]);

Creating the controller within a directive using the controller attribute:

myApp.directive ( 'myDirective', [ '$window', function( $window ) {
    return {
        restrict: 'A',
        controller: [ '$scope', function( $scope ) {

        }],
        link: function( scope, element, attrs ) {

        }
    };
}]);

Are there any specific reasons for not constructing the controller within a directive if they are both applied to the same element?

Could it depend on the complexity and usage frequency of the controller?

javascript angularjs angularjs-controller

Answer 1

Answer №1

The main rationale behind utilizing directive controllers can be summed up in a single sentence:

For the purpose of creating reusable components

A directive controller should encapsulate the logic of the component that has the potential to be reused. By combining a directive controller with an isolate scope, we are able to effectively generate reusable components.

Let's consider a paginator as an example: a paginator requires certain logic to communicate with other components (such as a grid) when the current selected page changes, enabling the grid to update accordingly. This type of logic can be included within the directive controller for reusability. When paired with an isolate scope, this scope is not bound to the application controller's scope, allowing for seamless configuration of the pageSize to connect to any property within the application controller's scope.

Answer 2

The main rationale behind utilizing directive controllers can be summed up in a single sentence:

For the purpose of creating reusable components

A directive controller should encapsulate the logic of the component that has the potential to be reused. By combining a directive controller with an isolate scope, we are able to effectively generate reusable components.

Let's consider a paginator as an example: a paginator requires certain logic to communicate with other components (such as a grid) when the current selected page changes, enabling the grid to update accordingly. This type of logic can be included within the directive controller for reusability. When paired with an isolate scope, this scope is not bound to the application controller's scope, allowing for seamless configuration of the pageSize to connect to any property within the application controller's scope.

Answer 3

Answer №2

There is a subtle distinction between a traditional controller (created using ng-controller or routes) and a directive controller.

A Directive controller has the ability to inject $element. While it is possible to inject $element into a traditional controller, this practice is generally discouraged.
The primary purpose of a directive controller is for communication between directives. An example can be seen on AngularJS's main page for tabs component.

A directive controller enables directives to possess functions. By being 'required' in other directives, these controller instances allow for communication and operation on the directive.

If your goal is directive-to-directive communication, then utilizing a controller with a directive is necessary. Otherwise, it is recommended to handle all scope logic within the linking function.

Answer 4

There is a subtle distinction between a traditional controller (created using ng-controller or routes) and a directive controller.

A Directive controller has the ability to inject $element. While it is possible to inject $element into a traditional controller, this practice is generally discouraged.
The primary purpose of a directive controller is for communication between directives. An example can be seen on AngularJS's main page for tabs component.

A directive controller enables directives to possess functions. By being 'required' in other directives, these controller instances allow for communication and operation on the directive.

If your goal is directive-to-directive communication, then utilizing a controller with a directive is necessary. Otherwise, it is recommended to handle all scope logic within the linking function.

Answer 5

Answer №3

Every time the directive is invoked, its controller function is also called.

<directive id="1"></directive>
<directive id="2"></directive>
<directive id="3"></directive>

The directive controller is called 3 times, each with its own scope.

The ngController behaves in a similar way, but it can be reused in other directives or HTML pages.

You can even include ngController within a directive (assuming that appCtrl is defined in some controller.js file).

.directive('directive',function(){
    return{
         scope:{},
         template:"<div>{{hello}}</div>",
         controller:"appCtrl"
    }
})

Answer 6

Every time the directive is invoked, its controller function is also called.

<directive id="1"></directive>
<directive id="2"></directive>
<directive id="3"></directive>

The directive controller is called 3 times, each with its own scope.

The ngController behaves in a similar way, but it can be reused in other directives or HTML pages.

You can even include ngController within a directive (assuming that appCtrl is defined in some controller.js file).

.directive('directive',function(){
    return{
         scope:{},
         template:"<div>{{hello}}</div>",
         controller:"appCtrl"
    }
})

Answer 7

Answer №4

Exploring the various ways to access methods and values within a directive controller:

Parent Directive

myApp.directive ( 'parent', [ function() {
    return {
        restrict: 'A',
        scope: {},
        controller: [ '$scope', function( $scope ) {
            //this.myVar = ''; //accessible in child directives
            //$scope.myVar = ''; //accessible in template
            $scope.myVar = this.myVar = '';
        }],
        template: '<div data-child> {{myVar}} </div>',
        link: function( scope, element, attrs ) {

            console.log( scope.myVar );

        }
    };
}]);

Child Directive

myApp.directive ( 'child', [ function() {
    return {
        restrict: 'A',
        require: '^parent',
        link: function( scope, element, attrs, ctrl ) {

            console.log( ctrl.myVar );

        }
    };
}]);

Answer 8

Exploring the various ways to access methods and values within a directive controller:

Parent Directive

myApp.directive ( 'parent', [ function() {
    return {
        restrict: 'A',
        scope: {},
        controller: [ '$scope', function( $scope ) {
            //this.myVar = ''; //accessible in child directives
            //$scope.myVar = ''; //accessible in template
            $scope.myVar = this.myVar = '';
        }],
        template: '<div data-child> {{myVar}} </div>',
        link: function( scope, element, attrs ) {

            console.log( scope.myVar );

        }
    };
}]);

Child Directive

myApp.directive ( 'child', [ function() {
    return {
        restrict: 'A',
        require: '^parent',
        link: function( scope, element, attrs, ctrl ) {

            console.log( ctrl.myVar );

        }
    };
}]);

Differences: Angular ngController vs Controller embedded in Directive

Answer №1

Answer №2

Answer №3

Answer №4

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