@ngdoc tutorial @name 13 - REST and Custom Services @step 13 @description In this step, we will change the way our application fetches data. * We define a custom service that represents a [RESTful][restful] client. Using this client we can make requests for data to the server in an easier way, without having to deal with the lower-level {@link ng.$http $http} API, HTTP methods and URLs.
## Dependencies The RESTful functionality is provided by Angular in the {@link ngResource ngResource} module, which is distributed separately from the core Angular framework. Since we are using [Bower][bower] to install client-side dependencies, this step updates the `bower.json` configuration file to include the new dependency:
**`bower.json`:** ``` { "name": "angular-phonecat", "description": "A starter project for AngularJS", "version": "0.0.0", "homepage": "https://github.com/angular/angular-phonecat", "license": "MIT", "private": true, "dependencies": { "angular": "1.5.x", "angular-mocks": "1.5.x", "angular-resource": "1.5.x", "angular-route": "1.5.x", "bootstrap": "3.3.x" } } ``` The new dependency `"angular-resource": "1.5.x"` tells bower to install a version of the angular-resource module that is compatible with version 1.5.x of Angular. We must tell bower to download and install this dependency. ``` npm install ```
**Note:** If you have bower installed globally, you can run `bower install`, but for this project we have preconfigured `npm install` to run bower for us.
**Warning:** If a new version of Angular has been released since you last ran `npm install`, then you may have a problem with the `bower install` due to a conflict between the versions of angular.js that need to be installed. If you run into this issue, simply delete your `app/bower_components` directory and then run `npm install`.
## Service We create our own service to provide access to the phone data on the server. We will put the service in its own module, under `core`, so we can explicitly declare its dependency on `ngResource`:
**`app/core/phone/phone.module.js`:** ```js angular.module('core.phone', ['ngResource']); ```
**`app/core/phone/phone.service.js`:** ```js angular. module('core.phone'). factory('Phone', ['$resource', function($resource) { return $resource('phones/:phoneId.json', {}, { query: { method: 'GET', params: {phoneId: 'phones'}, isArray: true } }); } ]); ``` We used the {@link angular.Module module API} to register a custom service using a factory function. We passed in the name of the service — `'Phone'` — and the factory function. The factory function is similar to a controller's constructor in that both can declare dependencies to be injected via function arguments. The `Phone` service declares a dependency on the `$resource` service, provided by the `ngResource` module. The {@link ngResource.$resource $resource} service makes it easy to create a [RESTful][restful] client with just a few lines of code. This client can then be used in our application, instead of the lower-level {@link ng.$http $http} service.
**`app/core/core.module.js`:** ```js angular.module('core', ['core.phone']); ``` We need to add the `core.phone` module as a dependency of the `core` module. ## Template Our custom resource service will be defined in `app/core/phone/phone.service.js`, so we need to include this file and the associated `.module.js` file in our layout template. Additionally, we also need to load the `angular-resource.js` file, which contains the `ngResource` module:
**`app/index.html`:** ```html ... ... ... ``` ## Component Controllers We can now simplify our component controllers (`PhoneListController` and `PhoneDetailController`) by factoring out the lower-level `$http` service, replacing it with the new `Phone` service. Angular's `$resource` service is easier to use than `$http` for interacting with data sources exposed as RESTful resources. It is also easier now to understand what the code in our controllers is doing.
**`app/phone-list/phone-list.module.js`:** ```js angular.module('phoneList', ['core.phone']); ```
**`app/phone-list/phone-list.component.js`:** ```js angular. module('phoneList'). component('phoneList', { templateUrl: 'phone-list/phone-list.template.html', controller: ['Phone', function PhoneListController(Phone) { this.phones = Phone.query(); this.orderProp = 'age'; } ] }); ```
**`app/phone-detail/phone-detail.module.js`:** ```js angular.module('phoneDetail', [ 'ngRoute', 'core.phone' ]); ```
**`app/phone-detail/phone-detail.component.js`:** ```js angular. module('phoneDetail'). component('phoneDetail', { templateUrl: 'phone-detail/phone-detail.template.html', controller: ['$routeParams', 'Phone', function PhoneDetailController($routeParams, Phone) { var self = this; self.phone = Phone.get({phoneId: $routeParams.phoneId}, function(phone) { self.setImage(phone.images[0]); }); self.setImage = function setImage(imageUrl) { self.mainImageUrl = imageUrl; }; } ] }); ``` Notice how in `PhoneListController` we replaced: ```js $http.get('phones/phones.json').then(function(response) { self.phones = response.data; }); ``` with just: ```js this.phones = Phone.query(); ``` This is a simple and declarative statement that we want to query for all phones. An important thing to notice in the code above is that we don't pass any callback functions, when invoking methods of our `Phone` service. Although it looks as if the results were returned synchronously, that is not the case at all. What is returned synchronously is a "future" — an object, which will be filled with data, when the XHR response is received. Because of the data-binding in Angular, we can use this future and bind it to our template. Then, when the data arrives, the view will be updated automatically. Sometimes, relying on the future object and data-binding alone is not sufficient to do everything we require, so in these cases, we can add a callback to process the server response. The `phoneDetail` component's controller illustrates this by setting the `mainImageUrl` in a callback. ## Testing Because we are now using the {@link ngResource ngResource} module, it is necessary to update the Karma configuration file with angular-resource.
**`karma.conf.js`:** ```js files: [ 'bower_components/angular/angular.js', 'bower_components/angular-resource/angular-resource.js', ... ], ``` We have added a unit test to verify that our new service is issuing HTTP requests and returns the expected "future" objects/arrays. The {@link ngResource.$resource $resource} service augments the response object with extra methods — e.g. for updating and deleting the resource — and properties (some of which are only meant to be accessed by Angular). If we were to use Jasmine's standard `.toEqual()` matcher, our tests would fail, because the test values would not match the responses exactly. To solve the problem, we instruct Jasmine to use a [custom equality tester][jasmine-equality] for comparing objects. We specify {@link angular.equals angular.equals} as our equality tester, which ignores functions and `$`-prefixed properties, such as those added by the `$resource` service.
(Remember that Angular uses the `$` prefix for its proprietary API.)
**`app/core/phone/phone.service.spec.js`:** ```js describe('Phone', function() { ... var phonesData = [...]; // Add a custom equality tester before each test beforeEach(function() { jasmine.addCustomEqualityTester(angular.equals); }); // Load the module that contains the `Phone` service before each test ... // Instantiate the service and "train" `$httpBackend` before each test ... // Verify that there are no outstanding expectations or requests after each test afterEach(function () { $httpBackend.verifyNoOutstandingExpectation(); $httpBackend.verifyNoOutstandingRequest(); }); it('should fetch the phones data from `/phones/phones.json`', function() { var phones = Phone.query(); expect(phones).toEqual([]); $httpBackend.flush(); expect(phones).toEqual(phonesData); }); }); ``` Here we are using `$httpBackend`'s {@link ngMock.$httpBackend#verifyNoOutstandingExpectation verifyNoOutstandingExpectation()} and {@link ngMock.$httpBackend#verifyNoOutstandingExpectation verifyNoOutstandingRequest()} methods to verify that all expected requests have been sent and that no extra request is scheduled for later. Note that we have also modified our component tests to use the custom matcher when appropriate. You should now see the following output in the Karma tab: ``` Chrome 49.0: Executed 5 of 5 SUCCESS (0.123 secs / 0.104 secs) ``` # Summary Now that we have seen how to build a custom service as a RESTful client, we are ready for {@link step_14 step 14} to learn how to enhance the user experience with animations. [bower]: http://bower.io/ [jasmine-equality]: https://jasmine.github.io/2.4/custom_equality.html [restful]: https://en.wikipedia.org/wiki/Representational_State_Transfer