Exercise: Facebook login with Sinatra

Facebook Login with Sinatra

Facebook Developer Console

To set up an application to use Facebook's authentication, first, navigate to Facebook Developers and follow these steps:

My Apps > Add a New App
Choose www (Website)
Click "Create App ID"

Set the platform

Since we'll be working locally, we have to specify our local host address for this application. Navigate to 'Settings' and click on Add Platform. Add to Site URL:

http://localhost:4567

Click Next

Add details

We need to configure some additional details for our app now. At the top, click "Skip quick start" or you can find your newly created app in "My Apps" to configure further.

Display Name (Not Unique): Sinatra Authentication App
Namespace (Unique): miked_auth_example_app
Choose category: Education

Set up the Sinatra application

Sublime Editor

Let's switch to Sublime real quick and paste in the code they presented before finishing the app setup in Facebook.

Create a new folder to store the application
Create the public and views folders
Create the Gemfile

source 'https://rubygems.org'

gem 'sinatra'
gem 'sinatra-contrib'

Create the app controller

# app.rb
require 'sinatra'
require 'sinatra/reloader'

get '/' do
  erb :index
end

Create the main view with the example login code given to us here: https://developers.facebook.com/docs/facebook-login/web

NOTE In the app configuration, copy the App Id assigned to you by Facebook. We'll need to use it in the starter code below.

<!DOCTYPE html>
<html>
<head>
<title>Facebook Login JavaScript Example</title>
<meta charset="UTF-8">
</head>
<body>
<script>
  // This is called with the results from from FB.getLoginStatus().
  function statusChangeCallback(response) {
    console.log('statusChangeCallback');
    console.log(response);
    // The response object is returned with a status field that lets the
    // app know the current login status of the person.
    // Full docs on the response object can be found in the documentation
    // for FB.getLoginStatus().
    if (response.status === 'connected') {
      // Logged into your app and Facebook.
      testAPI();
    } else if (response.status === 'not_authorized') {
      // The person is logged into Facebook, but not your app.
      document.getElementById('status').innerHTML = 'Please log ' +
        'into this app.';
    } else {
      // The person is not logged into Facebook, so we're not sure if
      // they are logged into this app or not.
      document.getElementById('status').innerHTML = 'Please log ' +
        'into Facebook.';
    }
  }

  // This function is called when someone finishes with the Login
  // Button.  See the onlogin handler attached to it in the sample
  // code below.
  function checkLoginState() {
    FB.getLoginStatus(function(response) {
      statusChangeCallback(response);
    });
  }

  window.fbAsyncInit = function() {
  FB.init({
    appId      : '{your app id here}',
    cookie     : true,  // enable cookies to allow the server to access 
                        // the session
    xfbml      : true,  // parse social plugins on this page
    version    : 'v2.2' // use version 2.2
  });

  // Now that we've initialized the JavaScript SDK, we call 
  // FB.getLoginStatus().  This function gets the state of the
  // person visiting this page and can return one of three states to
  // the callback you provide.  They can be:
  //
  // 1. Logged into your app ('connected')
  // 2. Logged into Facebook, but not your app ('not_authorized')
  // 3. Not logged into Facebook and can't tell if they are logged into
  //    your app or not.
  //
  // These three cases are handled in the callback function.

  FB.getLoginStatus(function(response) {
    statusChangeCallback(response);
  });

  };

  // Load the SDK asynchronously
  (function(d, s, id) {
    var js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return;
    js = d.createElement(s); js.id = id;
    js.src = "//connect.facebook.net/en_US/sdk.js";
    fjs.parentNode.insertBefore(js, fjs);
  }(document, 'script', 'facebook-jssdk'));

  // Here we run a very simple test of the Graph API after login is
  // successful.  See statusChangeCallback() for when this call is made.
  function testAPI() {
    console.log('Welcome!  Fetching your information.... ');
    FB.api('/me', function(response) {
      console.log('Successful login for: ' + response.name);
      document.getElementById('status').innerHTML =
        'Thanks for logging in, ' + response.name + '!';
    });
  }
</script>

<!--
  Below we include the Login Button social plugin. This button uses
  the JavaScript SDK to present a graphical Login button that triggers
  the FB.login() function when clicked.
-->

<fb:login-button scope="public_profile,email" onlogin="checkLoginState();">
</fb:login-button>

<div id="status">
</div>

</body>
</html>

Start the Sinatra server

$ bundle install
$ ruby app.rb

mdang/FACEBOOK_LOGIN.md

Select an option