step_07.ngdoc

@ngdoc tutorial
@name 7 - Routing & Multiple Views
@step 7
@description

<ul doc-tutorial-nav="7"></ul>


In this step, you will learn how to create a layout template and how to build an app that has
multiple views by adding routing, using an Angular module called 'ngRoute'.

* When you now navigate to `app/index.html`, you are redirected to `app/index.html/#/phones`
  and the phone list appears in the browser.
* When you click on a phone link, the url changes to that specific phone and the stub of a
  phone detail page is displayed.

<div doc-tutorial-reset="7"></div>

## Dependencies

The routing functionality added by this step is provided by angular in the `ngRoute` module, which
is distributed separately from the core Angular framework.

We are using [Bower][bower] to install client-side dependencies.  This step updates the
`bower.json` configuration file to include the new dependency:

```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": "1.4.x",
    "angular-mocks": "1.4.x",
    "jquery": "~2.2.1",
    "bootstrap": "~3.1.1",
    "angular-route": "1.4.x"
  }
}
```

The new dependency `"angular-route": "1.4.x"` tells bower to install a version of the
angular-route component that is compatible with version 1.4.x.  We must tell bower to download
and install this dependency.

If you have bower installed globally, then you can run `bower install` but for this project, we have
preconfigured npm to run bower install for us:

```
npm install
```

<div class="alert alert-warning">
  **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 get this then simply delete your `app/bower_components` folder before running
  `npm install`.
</div>

<div class="alert alert-info">
  **Note:** If you have bower installed globally then you can run `bower install` but for this project we have
  preconfigured `npm install` to run bower for us.
</div>


## Multiple Views, Routing and Layout Template

Our app is slowly growing and becoming more complex. Before step 7, the app provided our users with
a single view (the list of all phones), and all of the template code was located in the
`index.html` file. The next step in building the app is to add a view that will show detailed
information about each of the devices in our list.

To add the detailed view, we could expand the `index.html` file to contain template code for both
views, but that would get messy very quickly. Instead, we are going to turn the `index.html`
template into what we call a "layout template". This is a template that is common for all views in
our application. Other "partial templates" are then included into this layout template depending on
the current "route" — the view that is currently displayed to the user.

Application routes in Angular are declared via the {@link ngRoute.$routeProvider $routeProvider},
which is the provider of the {@link ngRoute.$route $route service}. This service makes it easy to
wire together controllers, view templates, and the current URL location in the browser. Using this
feature, we can implement [deep linking](http://en.wikipedia.org/wiki/Deep_linking), which lets us
utilize the browser's history (back and forward navigation) and bookmarks.


### A Note About DI, Injector and Providers

As you {@link tutorial/step_05 noticed}, {@link guide/di dependency injection} (DI) is at the core of
AngularJS, so it's important for you to understand a thing or two about how it works.

When the application bootstraps, Angular creates an injector that will be used to find and inject all
of the services that are required by your app. The injector itself doesn't know anything about what
`$http` or `$route` services do. In fact, the injector doesn't even know about the existence of these services
unless it is configured with proper module definitions.

The injector only carries out the following steps :

 * load the module definition(s) that you specify in your app
 * register all Providers defined in these module definitions
 * when asked to do so, inject a specified function and any necessary dependencies (services) that
   it lazily instantiates via their Providers.

Providers are objects that provide (create) instances of services and expose configuration APIs
that can be used to control the creation and runtime behavior of a service. In case of the `$route`
service, the `$routeProvider` exposes APIs that allow you to define routes for your application.

<div class="alert alert-warning">
**Note:** Providers can only be injected into `config` functions. Thus you could not inject
`$routeProvider` into `PhoneListCtrl`.
</div>

Angular modules solve the problem of removing global state from the application and provide a way
of configuring the injector. As opposed to AMD or require.js modules, Angular modules don't try to
solve the problem of script load ordering or lazy script fetching. These goals are totally independent and
both module systems can live side by side and fulfill their goals.

To deepen your understanding of DI on Angular, see
[Understanding Dependency Injection](https://github.com/angular/angular.js/wiki/Understanding-Dependency-Injection).

## Template

The `$route` service is usually used in conjunction with the {@link ngRoute.directive:ngView
ngView} directive. The role of the `ngView` directive is to include the view template for the current
route into the layout template. This makes it a perfect fit for our `index.html` template.

<div class="alert alert-info">
**Note:** Starting with AngularJS version 1.2, `ngRoute` is in its own module and must be loaded by
loading the additional `angular-route.js` file, which we download via Bower above.
</div>

__`app/index.html`:__

```html
<!doctype html>
<html lang="en" ng-app="phonecatApp">
<head>
...
  <script src="bower_components/angular/angular.js"></script>
  <script src="bower_components/angular-route/angular-route.js"></script>
  <script src="js/app.js"></script>
  <script src="js/controllers.js"></script>
</head>
<body>

  <div ng-view></div>

</body>
</html>
```

We have added two new `<script>` tags in our index file to load up extra JavaScript files into our
application:

- `angular-route.js` : defines the Angular `ngRoute` module, which provides us with routing.
- `app.js` : this file now holds the root module of our application.

Note that we removed most of the code in the `index.html` template and replaced it with a single
line containing a div with the `ng-view` attribute. The code that we removed was placed into the
`phone-list.html` template:

__`app/partials/phone-list.html`:__

```html
<div class="container-fluid">
  <div class="row">
    <div class="col-md-2">
      <!--Sidebar content-->

      Search: <input ng-model="query">
      Sort by:
      <select ng-model="orderProp">
        <option value="name">Alphabetical</option>
        <option value="age">Newest</option>
      </select>

    </div>
    <div class="col-md-10">
      <!--Body content-->

      <ul class="phones">
        <li ng-repeat="phone in phones | filter:query | orderBy:orderProp" class="thumbnail">
          <a href="#/phones/{{phone.id}}" class="thumb"><img ng-src="{{phone.imageUrl}}"></a>
          <a href="#/phones/{{phone.id}}">{{phone.name}}</a>
          <p>{{phone.snippet}}</p>
        </li>
      </ul>

    </div>
  </div>
</div>
```

<div style="display:none">
TODO!
<img  class="diagram" src="img/tutorial/tutorial_07_final.png">
</div>

We also added a placeholder template for the phone details view:

__`app/partials/phone-detail.html`:__

```html
TBD: detail view for <span>{{phoneId}}</span>
```

Note how we are using the `phoneId` expression which will be defined in the `PhoneDetailCtrl` controller.

## The App Module

To improve the organization of the app, we are making use of Angular's `ngRoute` module and we've
moved the controllers into their own module `phonecatControllers` (as shown below).

We added `angular-route.js` to `index.html` and created a new `phonecatControllers` module in
`controllers.js`. That's not all we need to do to be able to use their code, however. We also have
to add the modules as dependencies of our app. By listing these two modules as dependencies of
`phonecatApp`, we can use the directives and services they provide.


__`app/js/app.js`:__

```js
var phonecatApp = angular.module('phonecatApp', [
  'ngRoute',
  'phonecatControllers'
]);

...
```

Notice the second argument passed to `angular.module`, `['ngRoute', 'phonecatControllers']`. This
array lists the modules that `phonecatApp` depends on.


```js
...

phonecatApp.config(['$routeProvider',
  function($routeProvider) {
    $routeProvider.
      when('/phones', {
        templateUrl: 'partials/phone-list.html',
        controller: 'PhoneListCtrl'
      }).
      when('/phones/:phoneId', {
        templateUrl: 'partials/phone-detail.html',
        controller: 'PhoneDetailCtrl'
      }).
      otherwise({
        redirectTo: '/phones'
      });
  }]);
```

Using the `phonecatApp.config()` method, we request the `$routeProvider` to be injected into our
config function and use the {@link ngRoute.$routeProvider#when `$routeProvider.when()`} method to
define our routes.

Our application routes are defined as follows:

* `when('/phones')`: The phone list view will be shown when the URL hash fragment is `/phones`. To
  construct this view, Angular will use the `phone-list.html` template and the `PhoneListCtrl`
  controller.

* `when('/phones/:phoneId')`: The phone details view will be shown when the URL hash fragment
  matches '/phones/:phoneId', where `:phoneId` is a variable part of the URL. To construct the phone
  details view, Angular will use the `phone-detail.html` template and the `PhoneDetailCtrl`
  controller.

* `otherwise({redirectTo: '/phones'})`:  triggers a redirection to `/phones` when the browser
  address doesn't match either of our routes.


We reused the `PhoneListCtrl` controller that we constructed in previous steps and we added a new,
empty `PhoneDetailCtrl` controller to the `app/js/controllers.js` file for the phone details view.


Note the use of the `:phoneId` parameter in the second route declaration. The `$route` service uses
the route declaration — `'/phones/:phoneId'` — as a template that is matched against the current
URL. All variables defined with the `:` notation are extracted into the
{@link ngRoute.$routeParams `$routeParams`} object.


## Controllers

__`app/js/controllers.js`:__

```js
var phonecatControllers = angular.module('phonecatControllers', []);

phonecatControllers.controller('PhoneListCtrl', ['$scope', '$http',
  function ($scope, $http) {
    $http.get('phones/phones.json').success(function(data) {
      $scope.phones = data;
    });

    $scope.orderProp = 'age';
  }]);

phonecatControllers.controller('PhoneDetailCtrl', ['$scope', '$routeParams',
  function($scope, $routeParams) {
    $scope.phoneId = $routeParams.phoneId;
  }]);
```

Again, note that we created a new module called `phonecatControllers`. For small AngularJS
applications, it's common to create just one module for all of your controllers if there are just a
few. As your application grows, it is quite common to refactor your code into additional modules.
For larger apps, you will probably want to create separate modules for each major feature of
your app.

Because our example app is relatively small, we'll just add all of our controllers to the
`phonecatControllers` module.


## Test

To automatically verify that everything is wired properly, we wrote end-to-end tests that navigate
to various URLs and verify that the correct view was rendered.

```js
...
   it('should redirect index.html to index.html#/phones', function() {
    browser.get('app/index.html');
    browser.getLocationAbsUrl().then(function(url) {
        expect(url).toEqual('/phones');
      });
  });

  describe('Phone list view', function() {
    beforeEach(function() {
      browser.get('app/index.html#/phones');
    });
...

  describe('Phone detail view', function() {

    beforeEach(function() {
      browser.get('app/index.html#/phones/nexus-s');
    });


    it('should display placeholder page with phoneId', function() {
      expect(element(by.binding('phoneId')).getText()).toBe('nexus-s');
    });
  });
```


You can now rerun `npm run protractor` to see the tests run.


# Experiments

* Try to add an `{{orderProp}}` binding to `index.html`, and you'll see that nothing happens even
when you are in the phone list view. This is because the `orderProp` model is visible only in the
scope managed by `PhoneListCtrl`, which is associated with the `<div ng-view>` element. If you add
the same binding into the `phone-list.html` template, the binding will work as expected.

<div style="display: none">
* In `PhoneCatCtrl`, create a new model called "`hero`" with `this.hero = 'Zoro'`. In
`PhoneListCtrl`, let's shadow it with `this.hero = 'Batman'`. In `PhoneDetailCtrl`, we'll use
`this.hero = "Captain Proton"`. Then add the `<p>hero = {{hero}}</p>` to all three of our templates
(`index.html`, `phone-list.html`, and `phone-detail.html`). Open the app and you'll see scope
inheritance and model property shadowing do some wonders.
</div>


# Summary

With the routing set up and the phone list view implemented, we're ready to go to {@link step_08
step 8} to implement the phone details view.


<ul doc-tutorial-nav="7"></ul>


[bower]: http://bower.io