ng-book

Services 159
Now, anywhere that we need to access the GitHub API, we no longer need to call it through $http;
we can call the githubService instead and let it handle the complexities of dealing with the remote
service.
The GitHub API exposes the activity stream for the user on GitHub (this stream is simply a list of
recent events that a user has logged on GitHub). In our service, we can create a method that accesses
this API and exposes the resulting set to our API.
To expose a method on our service, we can place it as an attribute on the service object.
angular.module('myApp.services', [])
.factory('githubService', function($http) {
var githubUrl = 'https://api.github.com';
var runUserRequest = function(username, path) {
// Return the promise from the $http service
// that calls the Github API using JSONP
return $http({
method: 'JSONP',
url: githubUrl + '/users/' +
username + '/' +
path + '?callback=JSON_CALLBACK'
});
}
// Return the service object with a single function
// events
return {
events: function(username) {
return runUserRequest(username, 'events');
}
};
});
The githubService contains a single method that the components in our application can call.
Using Services
To use a service, we need to identify it as a dependency for the component where we’re using it: a
controller, a directive, a filter, or another service. At run time, Angular will take care of instantiating
it and resolving dependencies like normal.
To inject the service in the controller, we pass the name as an argument to the controller function.
With the dependency listed in the controller, we can execute any of the methods we define on the
service object.