Using the $injector instance directly vs. obtaining dependencies as parameters

Question

Within Angular, is it considered a good practice getting the dependencies directly from an $injector instance, rather than as parameters?

I have the problem that my controllers started having a lot of dependencies, so rather than:

myApp.controller(['$scope', 'Dep1', 'Dep2', 'Dep3', function($scope, Dep1, Dep2, Dep3) {
    ...
}]);

I would do:

myApp.controller(['$scope', '$injector', function($scope, $injector) {
    var Dep1 = $injector.get('Dep1');
    var Dep2 = $injector.get('Dep2');
    var Dep3 = $injector.get('Dep3');
}]);

I find it the same functionality-wise, but with much less clutter on the parameters. I suppose that this will make my components slightly less easy to test though, right?

What do you think?

If you always have to use Dep1,Dep2,Dep3 in multiple controllers. You could create a service that exports those as properties, and then just depend upon that 1 service. — Reactgular, Mar 22 '15 at 13:22
Testing is a factor. The real issue is that a large number of dependencies often indicates that your controllers are doing too much. What constitutes "large" depends on the individual case. — Cerad, Mar 22 '15 at 13:24

score 5 · Accepted Answer · edited May 23 '17 at 12:22

Based on my opinion and after reading the following posts:

Post 1

Post 2

Angular's documentation on DI (Dependency Injection)

Your second approach in order to minimize the long dependency list is considered as Service Locator Anti Pattern. See - Service locator AntiPattern

Using the Service Locator Anti Pattern is bad because it will make your life as a maintenance developer worse because you will need to use considerable amounts of brain power to grasp the implications of every change you make. Using the $injector obfuscates the actual dependencies of the resource (in this case controller) and kills maintainability.

In addition, according to angular's documentation the the preferable way is:

Using the inline array annotation (preferred)

If your controller is ending up using so many dependencies maybe you are doing something wrong, Maybe you broke the Single responsibility principle. consider:

Delegate more of the logic to service(s) that are injected in
Separate out into different controllers, so each only has (just about) 1 responsibility

score 0 · Answer 2 · answered Mar 22 '15 at 13:25

It depends how you write the code and how is easy to you and make you flexible to write code. I always write the controllers in this way hope it will help :}

var appCtrl = function($scope, others){...}
app.controller('appCtrl',['$scope', 'others', appCtrl]);

Using the $injector instance directly vs. obtaining dependencies as parameters

2 Answers2