@workInProgress
@ngdoc overview
@name Tutorial: Step 4
@description
<table id="tutorial_nav">
<tr>
<td id="previous_step">{@link tutorial.step_00 Previous}</td>
<td id="step_result">{@link  http://angular.github.com/angular-phonecat/step-4/app Example}</td>
<td id="tut_home">{@link tutorial Tutorial Home}</td>
<td id="code_diff">{@link https://github.com/angular/angular-phonecat/compare/step-3...step-4 Code
Diff}</td>
<td id="next_step">{@link tutorial.step_00 Next}</td>
</tr>
</table>

In this step, we add a feature that lets our users choose which way to order the phone list.

__`app/index.html`:__
<pre>
...
  <ul class="predicates">
    <li>
      Search: <input type="text" name="query"/>
    </li>
    <li>
      Sort by:
      <select name="orderProp">
        <option value="name">Alphabetical</option>
        <option value="age">Newest</option>
      </select>
    </li>
  </ul>

  <ul class="phones">
    <li ng:repeat="phone in phones.$filter(query).$orderBy(orderProp)">
      {{phone.name}}
      <p>{{phone.snippet}}</p>
    </li>
  </ul>
...
</pre>

__`app/js/controller.js`:__
<pre>
/* App Controllers */

function PhoneListCtrl() {
  this.phones = [{"name": "Nexus S",
                  "snippet": "Fast just got faster with Nexus S.",
                  "age": 0},
                 {"name": "Motorola XOOM™ with Wi-Fi",
                  "snippet": "The Next, Next Generation tablet.",
                  "age": 1},
                 {"name": "MOTOROLA XOOM™",
                  "snippet": "The Next, Next Generation tablet.",
                  "age": 2}];

  this.orderProp = 'age';
}
</pre>

__`test/unit/controllerSpec.js`:__
<pre>
/* jasmine specs for controllers go here */
describe('PhoneCat controllers', function() {

  describe('PhoneListCtrl', function(){
    var scope, $browser, ctrl;

    beforeEach(function() {
      ctrl = new PhoneListCtrl();
    });


    it('should create "phones" model with 3 phones', function() {
      expect(ctrl.phones.length).toBe(3);
    });


    it('should set the default value of orderProp model', function() {
      expect(ctrl.orderProp).toBe('age');
    });
  });
});
</pre>

__`test/e2e/scenarios.js`:__
<pre>
/* jasmine-like end2end tests go here */
describe('PhoneCat App', function() {

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

    beforeEach(function() {
      browser().navigateTo('../../app/index.html');
    });


    it('should filter the phone list as user types into the search box', function() {
      expect(repeater('.phones li').count()).toBe(3);

      input('query').enter('nexus');
      expect(repeater('.phones li').count()).toBe(1);

      input('query').enter('motorola');
      expect(repeater('.phones li').count()).toBe(2);
    });


    it('should be possible to control phone order via the drop down select box', function() {
      input('query').enter('tablet'); //let's narrow the dataset to make the test assertions
      shorter

      expect(repeater('.phones li', 'Phone List').column('a')).
          toEqual(["Motorola XOOM\u2122 with Wi-Fi",
                   "MOTOROLA XOOM\u2122"]);

      select('orderProp').option('alphabetical');

      expect(repeater('.phones li', 'Phone List').column('a')).
          toEqual(["MOTOROLA XOOM\u2122",
                   "Motorola XOOM\u2122 with Wi-Fi"]);
    });
  });
});
</pre>

## Discussion:

To provide dynamic ordering, we employ another one of angular's "array type augmenters" and let
the data binding do the rest of the work for us:

* First, we provide a `<select>` element named `orderProp` for our users so they can choose to
sort the phone list either alphabetically or by the age of the phone.  We added the `age` property
to each phone record so we can sort by that field.

* Like {@link angular.Array.filter $filter}, {@link angular.Array.orderBy $orderBy} is a built-in
method available on array objects in angular expressions.  In our UI template, we set up a select
box that lets the user set the `orderProp` model variable to one of the string constants: `age` or
`name`.

* In our controller, we added a line to set the default value of `orderProp` to `age`.  If we
don't override the default value, angular uses the value of the first `<option>` element when it
initializes the data model.

* Our unit test now verifies that our default ordering property is set.

* We added an end-to-end test to verify that our select box ordering mechanism works properly.

* Once again we added a little more CSS to improve the View.

<table id="tutorial_nav">
<tr>
<td id="previous_step">{@link tutorial.step_00 Previous}</td>
<td id="step_result">{@link  http://angular.github.com/angular-phonecat/step-4/app Example}</td>
<td id="tut_home">{@link tutorial Tutorial Home}</td>
<td id="code_diff">{@link https://github.com/angular/angular-phonecat/compare/step-3...step-4 Code
Diff}</td>
<td id="next_step">{@link tutorial.step_00 Next}</td>
</tr>
</table>