<h1 id="lab_7_user_identity">Access User's Data</h1>

<p>Most modern applications are attached to the web to synchronize data. When synchronizing data, you need to identify who the user is.
Chrome packaged apps come with an <a href="experimental.identity.html">identity API</a> that makes it easy to integrate either with Google accounts or with any other service that supports OAuth.</p>

<ol>
<li> Built in - Google Authenticiation</li>
<li> Third Party Authentication (Twitter, Foursquare, etc.)</li>
</ol>

<p class="warning"><b>Warning:</b>
Apps with authentication require the experimental permission in the
<code>manifest.json</code> and, until they came out of experimental state,
they cannot be uploaded to the Chrome Web Store.
If you prefer, you can choose to skip this lab.</p>

<h2 id="authenticating_with_google">Authenticating with Google</h2>

<p>We are working on a very easy integration flow for apps that authenticate with Google accounts. However, this flow is not yet available for general use. In the meantime, you may still use the third-party flow described below, even for Google services.</p>

<h2 id="integrating_with_a_third_party_service">Integrating with a third-party service</h2>

<p>Chrome packaged apps have a dedicated API for lauching the authentication flow to any third-party OAuth2 service, called $ref:experimental.identity.launchWebAuthFlow.
To show how this flow works, we&#39;re going to update our sample to import <a href="https://developers.google.com/google-apps/tasks/">Google Tasks</a> into the Todo list.</p>

<h3 id="register_with_the_provider">Register with the provider</h3>

<p>To use a third-party OAuth2 provider, you will first need to register your application with the provider. Each provider has a different way of registering applications, but in general it will be in a section called Developer or API at the provider&#39;s website.</p>

<p>Here we are treating Google as a third-party service. Just follow Google&#39;s own registration procedure for apps requiring API access below:</p>

<ol>
<li>Create a new project in the <a href="https://code.google.com/apis/console">Google API console</a>.</li>
<li>Activate the Tasks API on the Services secion.</li>
<li>Create a new OAuth2.0 client ID on API Access section. Select Web application and leave other fields unchanged.</li>
<li>Click on Edit settings for the newly created client ID.</li>
<li>In Authorized Redirect URLs, add <code>https://&lt;YOURAPP_ID&gt;.chromiumapp.org/</code>,
replacing &lt;YOURAPP_ID&gt; with your app ID (this is the app&#39;s long alphanumeric ID you can find in <code>chrome://extensions</code>).</li>
</ol>

<h3 id="add_permissions">Add permissions</h3>

<p>Update the
<a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/angularjs/manifest.json">AngularJS manifest.json</a> or
<a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/javascript/manifest.json">JavaScript manifest.json</a>
to use &quot;experimental&quot; features.
Note that we&#39;ve also requested permission
to make XHR requests to the Tasks service URL - for security reasons,
you need to request explicit permission in the manifest for every URL you will call via XHR.
</p>

<pre>
{
     ... ,
     &quot;permissions&quot;: [&quot;storage&quot;, &quot;experimental&quot;, &quot;https://www.googleapis.com/tasks/*&quot;]
}
</pre>

<h3 id="add_google_tasks_to_the_todo_list">Add Google tasks to the Todo list</h3>

<p>Now we are ready to ask user&#39;s authorization, so we can connect to the Tasks service and import his tasks into our Todo list. First, we will need to request an access token - which, at the first run will automatically pops up an authentication and authorization window to the user.
Once we have this token, we are able to call the Google Tasks API directly.</p>

<ol>
<li><p>Since this is time consuming and error prone, you can cheat and copy our JavaScript that handles the authentication to the Google Tasks API from here: <a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/angularjs/gapi_tasks.js">Angular gapi_tasks.js</a>
and <a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/javascript/gapi_tasks.js">JavaScript gapi_tasks.js</a> are the same.
This script calls <code>launchWebFlow</code> and
gets a valid access token for the specified client ID.
It also has simple JavaScript methods that, after authenticated,
goes to the Tasks API and gets the user&#39;s task lists and the corresponding tasks. </p>

<p class="note"><b>Note:</b> This script is NOT intented to be used in production - it is just a very simple, limited and definitely not robust piece of code intented to highlight the basic authentication and API calls.</p></li>
<li><p>Add a new method to the existing
<a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/angularjs/controller.js">AngularJS controller.js</a> or
<a href="https://github.com/GoogleChrome/chrome-app-codelab/blob/master/lab7_useridentification/javascript/controller.js">JavaScript controller.js</a> that,
using the methods from the script of the previous step,
authenticates the user and imports his Google tasks into the Todo list:
</p>

<tabs data-group="source">

  <header tabindex="0" data-value="angular">Angular</header>
  <header tabindex="0" data-value="js">JavaScript</header>

  <content>
    <pre>
$scope.importFromGTasks = function() {
  var api = new TasksAPI();
  var clientId = &quot;&lt;GET_YOURS_AT_https://code.google.com/apis/console&gt;&quot;;
  api.authenticate(clientId, function() {
    api.getLists(function(result) {
      console.log(result);
      if (!result || !result.items || result.items.length==0) {
        throw &quot;No task lists available&quot;;
      }
      var listId=result.items[0].id;
      api.getTasks(listId, function(tasks) {
        console.log(tasks);
        for (var j=0; j&lt;tasks.items.length; j++) {
          $scope.$apply(function() {
            $scope.todos.push({text:tasks.items[j].title, done:tasks.items[j].status!=&quot;needsAction&quot;});
          });
        }
      });
    });
  });
}
    </pre>
  </content>
  <content>
    <pre>
  document.getElementById('importGTasks').addEventListener('click', function() {
    var api = new TasksAPI();
    var clientId = &quot;&lt;GET_YOURS_AT_https://code.google.com/apis/console&gt;&quot;;
    api.authenticate(clientId, function() {
      api.getLists(function(result) {
        console.log(result);
        if (!result || !result.items || result.items.length==0) {
          throw "No task lists available";
        }
        var listId=result.items[0].id;
        api.getTasks(listId, function(tasks) {
          console.log(tasks);
          for (var j=0; j&lt;tasks.items.length; j++) {
            model.addTodo(tasks.items[j].title, tasks.items[j].status!='needsAction');
          }
        });
      });
    });
  });
    </pre>

</tabs>

<p>Replace the following line in the code above:
<pre>
  var clientId = &quot;&lt;GET_YOURS_AT_https://code.google.com/apis/console&gt;&quot;;
</pre>
with your own project&#39;s Client ID that you got from the Google API Console.
Should look like this:
<pre>
  var clientId = &quot;xxxxxxxxxxxxxx.apps.googleusercontent.com&quot;;
</pre></p></li>
<li><p>Now we just need a button that starts the import process. Update the <code>index.html</code> to include <code>gapi_tasks.js</code> and add a new button to call <code>importFromGTasks</code>:
</p>

<tabs data-group="source">

  <header tabindex="0" data-value="angular">Angular</header>
  <header tabindex="0" data-value="js">JavaScript</header>

  <content>
    <pre>
&lt;script src=&quot;gapi_tasks.js&quot;&gt;&lt;/script&gt;
...
&lt;button ng-click=&quot;importFromGTasks()&quot;&gt;import tasks from GTasks&lt;/button&gt;
    </pre>
  </content>
  <content>
    <pre>
&lt;button id="importGTasks"&gt;import tasks from GTasks&lt;/button&gt;
...
&lt;script src="gapi_tasks.js"&gt;&lt;/script&gt;
    </pre>
  </content>

</tabs></li>
</ol>

<h3 id="results">Check the results</h3>

<p>If you get stuck and want to see the app in action,
go to <code>chrome://extensions</code>,
load the unpacked
<a href="https://github.com/GoogleChrome/chrome-app-codelab/tree/master/lab7_useridentification/angularjs">AngularJS app</a> or
<a href="https://github.com/GoogleChrome/chrome-app-codelab/tree/master/lab7_useridentification/javascript">JavaScript app</a>,
and launch the app from a new tab.</p>

<h2 id="you_should_also_read">You should also read</h2>

<p><a href="app_identity.html">Identify User</a> tutorial</p>

<h2 id="what_39_s_next_">What's next?</h2>

<p>In <a href="app_codelab8_webresources.html">7 - Access Web Resources</a>,
you will learn how to load and show images from a remote URL.</p>

<p class="note"><b>Note:</b>  Up until now, the code in each lab builds upon the previous lab code sample.
We&#39;ve decided not to include the user identification code changes in the remainder of the lab since the <code>identity API</code> is still experimental and as such it would prevent you from publishing your final code to the Chrome Web Store.</p>