Tutorial: 2 - Angular Template

Now it's time to make this web page dynamic with angular. We'll also add a test that verifies the code for the controller we are going to add.

There are many ways to structure the code for an application. With angular, we encourage the use of the MVC design pattern to decouple the code and separate concerns. With that in mind, let's use a little angular and JavaScript to add model, view, and controller components to our app.

The app now contains a list with 3 phones.

The most important changes are listed below. You can see the full diff on GitHub:

Template for the View

The view component is constructed by angular from this template:

app/index.html:

...
<body ng:controller="PhoneListCtrl">


  <ul>
    <li ng:repeat="phone in phones">
      {{phone.name}}
      <p>{{phone.snippet}}</p>
    </li>
  </ul>


  <script src="lib/angular/angular.js" ng:autobind></script>
  <script src="js/controllers.js"></script>
</body>
</html>

We replaced the hard-coded phone list with the ng:repeat widget and two angular expressions enclosed in curly braces: {{phone.name}} and {{phone.snippet}}:

Model and Controller

The data model (a simple array of phones in object literal notation) is instantiated within the controller function (PhoneListCtrl):

app/js/controllers.js:

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

Although the controller is not yet doing very much controlling, it is playing a crucial role. By providing context for our data model, the controller allows us to establish data-binding between the model and the view. Note in the following how we connected the dots between our presentation, data, and logic components:

Angular scopes are a crucial concept in angular; you can think of scopes as the glue that makes the template, model and controller all work together. Angular uses scopes, along with the information contained in the template, data model, and controller, to keep the model and view separated but in sync. Any changes to the model are reflected in the view; any changes that occur in the view are reflected in the model. To learn more about angular scopes, see the angular scope documentation.

Tests

The "Angular way" makes it easy for us to test as we develop; the unit test for your newly created controller looks as follows:

test/unit/controllersSpec.js:

describe('PhoneCat controllers', function() {


  describe('PhoneListCtrl', function() {


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

Ease of testing is another cornerstone of angular's design philosophy. All we are doing here is showing how easy it is to create a unit test. The test verifies that we have 3 records in the phones array.

Angular developers prefer the syntax of Jasmine's Behavior-driven Development (BDD) framework when writing tests. Although Jasmine is not required by angular, we used it to write all tests in this tutorial. You can learn about Jasmine on the Jasmine home page and on the Jasmine wiki.

The angular-seed project is pre-configured to run all unit tests using JsTestDriver. To run the test, do the following:

  1. In a separate terminal window or tab, go to the angular-phonecat directory and run ./scripts/test-server.sh to start the test web server.

  2. Open a new browser tab or window and navigate to http://localhost:9876.

  3. Choose "Capture this browser in strict mode".

    At this point, you can leave this tab open and forget about it. JsTestDriver will use it to execute the tests and report the results in the terminal.

  4. Execute the test by running ./scripts/test.sh

    You should see the following or similar output:

         Chrome: Runner reset.
         .
         Total 1 tests (Passed: 1; Fails: 0; Errors: 0) (2.00 ms)
           Chrome 11.0.696.57 Mac OS: Run 1 tests (Passed: 1; Fails: 0; Errors 0) (2.00 ms)
    

    Yay! The test passed! Or not...

    Note: If you see errors after you run the test, close the browser tab and go back to the terminal and kill the script, then repeat the procedure above.

Experiments

Summary

You now have a dynamic app that features separate model, view, and controller components, and you're testing as you go. Now, let's go to step 3 to learn how to add full text search to the app.