What’s the recommended way to extend AngularJS controllers?

What’s the recommended way to extend AngularJS controllers?

I have three controllers that are quite similar. I want to have a controller which these three extend and share its functions.

Solutions/Answers:

Solution 1:

Perhaps you don’t extend a controller but it is possible to extend a controller or make a single controller a mixin of multiple controllers.

module.controller('CtrlImplAdvanced', ['$scope', '$controller', function ($scope, $controller) {
    // Initialize the super class and extend it.
    angular.extend(this, $controller('CtrlImpl', {$scope: $scope}));
    … Additional extensions to create a mixin.
}]);

When the parent controller is created the logic contained within it is also executed.
See $controller() for for more information about but only the $scope value needs to be passed. All other values will be injected normally.

@mwarren, your concern is taken care of auto-magically by Angular dependency injection. All you need is to inject $scope, although you could override the other injected values if desired.
Take the following example:

(function(angular) {

	var module = angular.module('stackoverflow.example',[]);

	module.controller('simpleController', function($scope, $document) {
		this.getOrigin = function() {
			return $document[0].location.origin;
		};
	});

	module.controller('complexController', function($scope, $controller) {
		angular.extend(this, $controller('simpleController', {$scope: $scope}));
	});

})(angular);
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.3.15/angular.js"></script>

<div ng-app="stackoverflow.example">
    <div ng-controller="complexController as C">
        <span><b>Origin from Controller:</b> {{C.getOrigin()}}</span>
    </div>
</div>

Although $document is not passed into ‘simpleController’ when it is created by ‘complexController’ $document is injected for us.

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Solution 2:

For inheritance you can use standard JavaScript inheritance patterns.
Here is a demo which uses $injector

function Parent($scope) {
  $scope.name = 'Human';
  $scope.clickParent = function() {
    $scope.name = 'Clicked from base controller';
  }    
}

function Child($scope, $injector) {
  $injector.invoke(Parent, this, {$scope: $scope});
  $scope.name = 'Human Child';
  $scope.clickChild = function(){
    $scope.clickParent();
  }       
}

Child.prototype = Object.create(Parent.prototype);

In case you use the controllerAs syntax (which I highly recommend), it is even easier to use the classical inheritance pattern:

function BaseCtrl() {
  this.name = 'foobar';
}
BaseCtrl.prototype.parentMethod = function () {
  //body
};

function ChildCtrl() {
  BaseCtrl.call(this);
  this.name = 'baz';
}
ChildCtrl.prototype = Object.create(BaseCtrl.prototype);
ChildCtrl.prototype.childMethod = function () {
  this.parentMethod();
  //body
};

app.controller('BaseCtrl', BaseCtrl);
app.controller('ChildCtrl', ChildCtrl);

Another way could be to create just “abstract” constructor function which will be your base controller:

function BaseController() {
  this.click = function () {
    //some actions here
  };
}

module.controller('ChildCtrl', ['$scope', function ($scope) {
  BaseController.call($scope);
  $scope.anotherClick = function () {
    //other actions
  };
}]);

Blog post on this topic

Solution 3:

Well, I’m not exactly sure what you want to achieve, but usually Services are the way to go.
You can also use the Scope inheritance characteristics of Angular to share code between controllers:

<body ng-controller="ParentCtrl">
 <div ng-controller="FirstChildCtrl"></div>
 <div ng-controller="SecondChildCtrl"></div>
</body>

function ParentCtrl($scope) {
 $scope.fx = function() {
   alert("Hello World");
 });
}

function FirstChildCtrl($scope) {
  // $scope.fx() is available here
}

function SecondChildCtrl($scope) {
  // $scope.fx() is available here
}

Solution 4:

You don’t extend controllers. If they perform the same basic functions then those functions need to be moved to a service. That service can be injected into your controllers.

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Solution 5:

Yet another good solution taken from this article:

// base controller containing common functions for add/edit controllers
module.controller('Diary.BaseAddEditController', function ($scope, SomeService) {
    $scope.diaryEntry = {};

    $scope.saveDiaryEntry = function () {
        SomeService.SaveDiaryEntry($scope.diaryEntry);
    };

    // add any other shared functionality here.
}])

module.controller('Diary.AddDiaryController', function ($scope, $controller) {
    // instantiate base controller
    $controller('Diary.BaseAddEditController', { $scope: $scope });
}])

module.controller('Diary.EditDiaryController', function ($scope, $routeParams, DiaryService, $controller) {
    // instantiate base controller
    $controller('Diary.BaseAddEditController', { $scope: $scope });

    DiaryService.GetDiaryEntry($routeParams.id).success(function (data) {
        $scope.diaryEntry = data;
    });
}]);

Solution 6:

You can create a service and inherit its behaviour in any controller just by injecting it.

app.service("reusableCode", function() {

    var reusableCode = {};

    reusableCode.commonMethod = function() {
        alert('Hello, World!');
    };

    return reusableCode;
});

Then in your controller that you want to extend from the above reusableCode service:

app.controller('MainCtrl', function($scope, reusableCode) {

    angular.extend($scope, reusableCode);

    // now you can access all the properties of reusableCode in this $scope
    $scope.commonMethod()

});

DEMO PLUNKER: http://plnkr.co/edit/EQtj6I0X08xprE8D0n5b?p=preview