@ngdoc overview
@name Developer Guide: DI: Using DI in Controllers
@description

The most common place to use dependency injection in angular applications is in {@link
dev_guide.mvc.understanding_controller controllers}. Here is a simple example:

<pre>
function MyController($location){
 // do stuff with the $location service
}
MyController.$inject = ['$location'];
</pre>

In this example, the `MyController` constructor function takes one argument, the {@link
api/angular.module.ng.$location $location} service. Angular is then responsible for supplying the
instance of `$location` to the controller when the constructor is instantiated. There are two ways
to cause controller instantiation – by configuring routes with the `$location` service, or by
referencing the controller from the HTML template, as follows:

<pre>
<!doctype html>
<html ng-controller="MyController" ng-app>
<script src="http://code.angularjs.org/angular.min.js"></script>
<body>
 ...
</body>
</html>
</pre>

When angular is instantiating your controller, it needs to know what services, if any, should be
injected (passed in as arguments) into the controller. Since there is no reflection in JavaScript,
we have to supply this information to angular in the form of an additional property on the
controller constructor function called `$inject`. Think of it as annotations for JavaScript.

<pre>
MyController.$inject = ['$location'];
</pre>

The information in `$inject` is then used by the {@link api/angular.injector injector} to call the
function with the correct arguments.


## Related Topics

* {@link dev_guide.di About Dependency Injection}
* {@link dev_guide.di.understanding_di Understanding Dependency Injection in Angular}
* {@link dev_guide.services Angular Services}

## Related API

* {@link api/angular.injector Angular Injector API}
