Tutorial

Easy Node Authentication: Linking All Accounts Together

Draft updated on Invalid Date

Chris on Code

Easy Node Authentication: Linking All Accounts Together

This tutorial is out of date and no longer maintained.

Note: This article is part of our Easy Node Authentication series.

Getting Started and Local Authentication
Facebook
Twitter
Google
Linking All Accounts Together
Upgrading Our “Easy Node Authentication” Series to ExpressJS 4.0

Introduction

This will be the final article in our Easy Node Authentication Series. We will be using all of the previous articles together.

Note: Edit 11/18/2017: Updated to reflect Facebook API changes.

Linking Accounts Together

This article will combine all the different Node Passport Strategies so that a user will be able to have one account and link all their social networks together.

There are many changes that need to take place from the previous articles to accomplish this. Here are the main cases we have to account for when moving from authenticating with only 1 account versus multiple accounts.

Scenarios to Account For

Linking Accounts: Check if a user already exists in the database. If they do, then add a social account to their user profile
Account Creation: If a user does not exist in the database, then create a user profile
Unlinking: Unlinking social accounts
Reconnecting: If a user unlinked a social account, but wants to reconnect it

We’ll be going through each of these scenarios and updating our previous code to account for them.

What We’ll Be Coding

We’ll be working with the Local Strategy and the Facebook Strategy to demonstrate linking accounts. The tactics used for the Facebook Strategy will carry over to Twitter and Google.

In order to add linking accounts to our application, we will need to:

Update our Strategies
Add new routes
Update our views for linking and unlinking

User Model Explanation

When looking at the way we set up our user model, we deliberately set up all the user accounts to be set up within their own object. This ensures that we can link and unlink different accounts as our user sees fit. Notice that the social accounts will use token and id while our local account will use email and password.

app/models/user.js

    ...
    var userSchema = mongoose.Schema({

        local            : {
            email        : String,
            password     : String,
        },
        facebook         : {
            id           : String,
            token        : String,
            email        : String,
            name         : String
        },
        twitter          : {
            id           : String,
            token        : String,
            displayName  : String,
            username     : String
        },
        google           : {
            id           : String,
            token        : String,
            email        : String,
            name         : String
        }

    });
    ...

We have also added in email, name, displayName, and username for some accounts just to show that we can pull that information from the respective social connection.

Once a user has linked all their accounts together, they will have one user account in our database, with all of these fields full.

Authenticating vs Authorizing

When we originally made these Strategies, we would use passport.authenticate. This is what we should be using upon first authentication of our user. But what do we do if they are already logged in? They will be logged in and their user stored in session when we want to link them to their current account.

Luckily, Passport provides a way to “connect” a user’s account. They provide passport.authorize for users that are already authenticated. To read more on the usage, visit the Passport authorize docs.

We will update our routes to handle the authorization first, and then we’ll update our Passport Strategies to handle the authorization.

Routes

Let’s create our routes first so that we can see how we link everything together. In the past articles, we created our routes for authentication. Let’s create a second set of routes for authorization. Once we’ve done that, we’ll change our Strategy to accommodate the new scenarios.

Our old routes will be commented to make a cleaner file.

app/routes.js

    module.exports = function(app, passport) {

    // normal routes ===============================================================
        // show the home page (will also have our login links)
        // PROFILE SECTION =========================
        // LOGOUT ==============================

    // =============================================================================
    // AUTHENTICATE (FIRST LOGIN) ==================================================
    // =============================================================================

        // locally --------------------------------
            // LOGIN ===============================
            // show the login form
            // process the login form

            // SIGNUP =================================
            // show the signup form
            // process the signup form

        // facebook -------------------------------
            // send to facebook to do the authentication
            app.get('/auth/facebook', passport.authenticate('facebook', { scope : 'email' }));

            // handle the callback after facebook has authenticated the user
            app.get('/auth/facebook/callback',
                passport.authenticate('facebook', {
                    successRedirect : '/profile',
                    failureRedirect : '/'
                }));

        // twitter --------------------------------
            // send to twitter to do the authentication
            // handle the callback after twitter has authenticated the user

        // google ---------------------------------
            // send to google to do the authentication
            // the callback after google has authenticated the user

    // =============================================================================
    // AUTHORIZE (ALREADY LOGGED IN / CONNECTING OTHER SOCIAL ACCOUNT) =============
    // =============================================================================

        // locally --------------------------------
            app.get('/connect/local', function(req, res) {
                res.render('connect-local.ejs', { message: req.flash('loginMessage') });
            });
            app.post('/connect/local', passport.authenticate('local-signup', {
                successRedirect : '/profile', // redirect to the secure profile section
                failureRedirect : '/connect/local', // redirect back to the signup page if there is an error
                failureFlash : true // allow flash messages
            }));

        // facebook -------------------------------

            // send to facebook to do the authentication
            app.get('/connect/facebook', passport.authorize('facebook', {
              scope : ['public_profile', 'email']
            }));

            // handle the callback after facebook has authorized the user
            app.get('/connect/facebook/callback',
                passport.authorize('facebook', {
                    successRedirect : '/profile',
                    failureRedirect : '/'
                }));

        // twitter --------------------------------

            // send to twitter to do the authentication
            app.get('/connect/twitter', passport.authorize('twitter', { scope : 'email' }));

            // handle the callback after twitter has authorized the user
            app.get('/connect/twitter/callback',
                passport.authorize('twitter', {
                    successRedirect : '/profile',
                    failureRedirect : '/'
                }));


        // google ---------------------------------

            // send to google to do the authentication
            app.get('/connect/google', passport.authorize('google', { scope : ['profile', 'email'] }));

            // the callback after google has authorized the user
            app.get('/connect/google/callback',
                passport.authorize('google', {
                    successRedirect : '/profile',
                    failureRedirect : '/'
                }));
    };

    // route middleware to ensure user is logged in
    function isLoggedIn(req, res, next) {
        if (req.isAuthenticated())
            return next();

        res.redirect('/');
    }

As you can see, we have all the authentication routes and the routes to show our index and profile pages. Now we have added authorization routes which will look incredibly similar to our authentication routes.

With our newly created routes, let’s update the Strategy so that our authorization routes are utilized.

Updating Strategies

We will just update the Facebook and Local Strategies to get a feel for how we can accommodate all our different scenarios.

When using the passport.authorize route, our user that is stored in session (since they are already logged in) will be passed to the Strategy. We will make sure we change our code to account for that.

We’re going to show the old Strategy and then the new Strategy. Read the comments to get a full understanding of the changes.

Old Facebook Strategy

config/passport.js

    ...
        // =========================================================================
        // FACEBOOK ================================================================
        // =========================================================================
        passport.use(new FacebookStrategy({

            // pull in our app id and secret from our auth.js file
            clientID        : configAuth.facebookAuth.clientID,
            clientSecret    : configAuth.facebookAuth.clientSecret,
            callbackURL     : configAuth.facebookAuth.callbackURL

        },

        // facebook will send back the token and profile
        function(token, refreshToken, profile, done) {

            // asynchronous
            process.nextTick(function() {

                // find the user in the database based on their facebook id
                User.findOne({ 'facebook.id' : profile.id }, function(err, user) {

                    // if there is an error, stop everything and return that
                    // ie an error connecting to the database
                    if (err)
                        return done(err);

                    // if the user is found, then log them in
                    if (user) {
                        return done(null, user); // user found, return that user
                    } else {
                        // if there is no user found with that facebook id, create them
                        var newUser            = new User();

                        // set all of the facebook information in our user model
                        newUser.facebook.id    = profile.id; // set the users facebook id
                        newUser.facebook.token = token; // we will save the token that facebook provides to the user
                        newUser.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName; // look at the passport user profile to see how names are returned
                        newUser.facebook.email = profile.emails[0].value; // facebook can return multiple emails so we'll take the first

                        // save our user to the database
                        newUser.save(function(err) {
                            if (err)
                                throw err;

                            // if successful, return the new user
                            return done(null, newUser);
                        });
                    }

                });
            });

        }));
    ...

Now we want the ability to authorize a user.

New Facebook Strategy

    ...
        // =========================================================================
        // FACEBOOK ================================================================
        // =========================================================================
        passport.use(new FacebookStrategy({

            // pull in our app id and secret from our auth.js file
            clientID        : configAuth.facebookAuth.clientID,
            clientSecret    : configAuth.facebookAuth.clientSecret,
            callbackURL     : configAuth.facebookAuth.callbackURL,
            passReqToCallback : true // allows us to pass in the req from our route (lets us check if a user is logged in or not)

        },

        // facebook will send back the token and profile
        function(req, token, refreshToken, profile, done) {

            // asynchronous
            process.nextTick(function() {

                // check if the user is already logged in
                if (!req.user) {

                    // find the user in the database based on their facebook id
                    User.findOne({ 'facebook.id' : profile.id }, function(err, user) {

                        // if there is an error, stop everything and return that
                        // ie an error connecting to the database
                        if (err)
                            return done(err);

                        // if the user is found, then log them in
                        if (user) {
                            return done(null, user); // user found, return that user
                        } else {
                            // if there is no user found with that facebook id, create them
                            var newUser            = new User();

                            // set all of the facebook information in our user model
                            newUser.facebook.id    = profile.id; // set the users facebook id
                            newUser.facebook.token = token; // we will save the token that facebook provides to the user
                            newUser.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName; // look at the passport user profile to see how names are returned
                            newUser.facebook.email = profile.emails[0].value; // facebook can return multiple emails so we'll take the first

                            // save our user to the database
                            newUser.save(function(err) {
                                if (err)
                                    throw err;

                                // if successful, return the new user
                                return done(null, newUser);
                            });
                        }

                    });

                } else {
                    // user already exists and is logged in, we have to link accounts
                    var user            = req.user; // pull the user out of the session

                    // update the current users facebook credentials
                    user.facebook.id    = profile.id;
                    user.facebook.token = token;
                    user.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName;
                    user.facebook.email = profile.emails[0].value;

                    // save the user
                    user.save(function(err) {
                        if (err)
                            throw err;
                        return done(null, user);
                    });
                }

            });

        }));
    ...

Now we have accounted for linking an account if a user is already logged in. We still have the same functionality from before, now we just check if the user is logged in before we take action.

Linking Accounts

Using this new code in our Strategy, we will create a new user if they are not already logged in, or we will add our Facebook credentials to our user if they are currently logged in and stored in session.

Other Strategies: The code for the Facebook Strategy will be the same for Twitter and Google. Just apply that code to both of those to get this working. We will also provide the full code so you can look at and reference it.

Now that we have the routes that will pass our user to our new Facebook Strategy, let’s make sure our UI lets our user use the newly created routes.

We will update our index.ejs and our profile.ejs to show all the login buttons on the home page, and all the accounts and link buttons on the profile page. Here is the full code for both with the important parts highlighted.

Home Page index.ejs

views/index.ejs

    <!doctype html>
    <html>
    <head>
        <title>Node Authentication</title>
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css">
        <style>
            body        { padding-top:80px; }
        </style>
    </head>
    <body>
    <div class="container">

        <div class="jumbotron text-center">
            <h1><span class="fa fa-lock"></span> Node Authentication</h1>

            <p>Login or Register with:</p>

            <a href="/login" class="btn btn-default"><span class="fa fa-user"></span> Local Login</a>
            <a href="/signup" class="btn btn-default"><span class="fa fa-user"></span> Local Signup</a>
            <a href="/auth/facebook" class="btn btn-primary"><span class="fa fa-facebook"></span> Facebook</a>
            <a href="/auth/twitter" class="btn btn-info"><span class="fa fa-twitter"></span> Twitter</a>
            <a href="/auth/google" class="btn btn-danger"><span class="fa fa-google-plus"></span> Google+</a>
        </div>

    </div>
    </body>
    </html>

Profile Page profile.ejs

views/profile.ejs

    <!doctype html>
    <html>
    <head>
        <title>Node Authentication</title>
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css">
        <style>
            body        { padding-top:80px; word-wrap:break-word; }
        </style>
    </head>
    <body>
    <div class="container">

        <div class="page-header text-center">
            <h1><span class="fa fa-anchor"></span> Profile Page</h1>
            <a href="/logout" class="btn btn-default btn-sm">Logout</a>
        </div>

        <div class="row">

            <!-- LOCAL INFORMATION -->
            <div class="col-sm-6">
                <div class="well">
                    <h3><span class="fa fa-user"></span> Local</h3>

                    <% if (user.local.email) { %>
                        <p>
                            <strong>id</strong>: <%= user._id %><br>
                            <strong>email</strong>: <%= user.local.email %><br>
                            <strong>password</strong>: <%= user.local.password %>
                        </p>

                        <a href="/unlink/local" class="btn btn-default">Unlink</a>
                    <% } else { %>
                        <a href="/connect/local" class="btn btn-default">Connect Local</a>
                    <% } %>

                </div>
            </div>

            <!-- FACEBOOK INFORMATION -->
            <div class="col-sm-6">
                <div class="well">
                    <h3 class="text-primary"><span class="fa fa-facebook"></span> Facebook</h3>

                    <!-- check if the user has this token (is the user authenticated with this social account) -->
                    <% if (user.facebook.token) { %>
                        <p>
                            <strong>id</strong>: <%= user.facebook.id %><br>
                            <strong>token</strong>: <%= user.facebook.token %><br>
                            <strong>email</strong>: <%= user.facebook.email %><br>
                            <strong>name</strong>: <%= user.facebook.name %><br>
                        </p>

                        <a href="/unlink/facebook" class="btn btn-primary">Unlink</a>
                    <% } else { %>
                        <a href="/connect/facebook" class="btn btn-primary">Connect Facebook</a>
                    <% } %>

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

        <div class="row">

            <!-- TWITTER INFORMATION -->
            <div class="col-sm-6">
                <div class="well">
                    <h3 class="text-info"><span class="fa fa-twitter"></span> Twitter</h3>

                    <!-- check if the user has this token (is the user authenticated with this social account) -->
                    <% if (user.twitter.token) { %>
                        <p>
                            <strong>id</strong>: <%= user.twitter.id %><br>
                            <strong>token</strong>: <%= user.twitter.token %><br>
                            <strong>display name</strong>: <%= user.twitter.displayName %><br>
                            <strong>username</strong>: <%= user.twitter.username %>
                        </p>

                        <a href="/unlink/twitter" class="btn btn-info">Unlink</a>
                    <% } else { %>
                        <a href="/connect/twitter" class="btn btn-info">Connect Twitter</a>
                    <% } %>

                </div>
            </div>

            <!-- GOOGLE INFORMATION -->
            <div class="col-sm-6">
                <div class="well">
                    <h3 class="text-danger"><span class="fa fa-google-plus"></span> Google+</h3>

                    <!-- check if the user has this token (is the user authenticated with this social account) -->
                    <% if (user.google.token) { %>
                        <p>
                            <strong>id</strong>: <%= user.google.id %><br>
                            <strong>token</strong>: <%= user.google.token %><br>
                            <strong>email</strong>: <%= user.google.email %><br>
                            <strong>name</strong>: <%= user.google.name %>
                        </p>

                        <a href="/unlink/google" class="btn btn-danger">Unlink</a>
                    <% } else { %>
                        <a href="/connect/google" class="btn btn-danger">Connect Google</a>
                    <% } %>

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

    </div>
    </body>
    </html>

Now we will have the links to each of our login methods. Then after they have logged in with one, the profile will check which accounts are already linked and which are not.

If an account is not yet linked, it will show the Connect Button. If an account is already linked, then our view will show the account information and the unlink button.

Remember that our user is passed to our profile view from the routes.js file.

Connecting Local

Our social accounts can easily be configured this way. The only problem currently is if a user wanted to connect to a local account. The problem comes in because they will need to see a signup page to add their email and password.

We have already created a route to handle showing our new connection form (in our routes.js file: (app.get('connect/local'))). All we need to do is create the view that the route brings up.

Create a file in your views folder: views/connect-local.ejs.

views/connect-local.ejs

    <!doctype html>
    <html>
    <head>
        <title>Node Authentication</title>
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css">
        <style>
            body        { padding-top:80px; }
        </style>
    </head>
    <body>
    <div class="container">
    <div class="col-sm-6 col-sm-offset-3">

        <h1><span class="fa fa-user"></span> Add Local Account</h1>

        <% if (message.length > 0) { %>
            <div class="alert alert-danger"><%= message %></div>
        <% } %>

        <!-- LOGIN FORM -->
        <form action="/connect/local" method="post">
            <div class="form-group">
                <label>Email</label>
                <input type="text" class="form-control" name="email">
            </div>
            <div class="form-group">
                <label>Password</label>
                <input type="password" class="form-control" name="password">
            </div>

            <button type="submit" class="btn btn-warning btn-lg">Add Local</button>
        </form>

        <hr>

        <p><a href="/profile">Go back to profile</a></p>

    </div>
    </div>
    </body>
    </html>

This will look incredibly similar to our signup.ejs form. That’s because it really is. We pretty much just changed out the verbiage and the action URL for the form.

Now when someone tries to connect a local account, they will be directed to this form, and then when submitted, they will be directed to our Local Strategy. That links the accounts!

Linking Accounts Works!

With just those routes and the update to our Passport Strategies, our application can now link accounts together! Take a look at a user in our database that has all their accounts linked using Robomongo:

Unlinking Accounts

Linking accounts was easy. What about unlinking? Let’s say a user no longer wants their Facebook account linked.

For our purposes, when a user wants to unlink an account, we will remove their token only. We will keep their id in the database just in case they realize their mistake of leaving and want to come back to join our application.

We can do this all in our routes file. You are welcome to create a controller and do all this logic there. Then you would just call the controller from the routes. For simplicity’s sake, we’ll throw that code directly into our routes.

Let’s add our unlinking routes after our newly created authorization routes.

app/routes.js

    ...

    // normal routes
    // authentication routes
    // authorization routes

    // =============================================================================
    // UNLINK ACCOUNTS =============================================================
    // =============================================================================
    // used to unlink accounts. for social accounts, just remove the token
    // for local account, remove email and password
    // user account will stay active in case they want to reconnect in the future

        // local -----------------------------------
        app.get('/unlink/local', function(req, res) {
            var user            = req.user;
            user.local.email    = undefined;
            user.local.password = undefined;
            user.save(function(err) {
                res.redirect('/profile');
            });
        });

        // facebook -------------------------------
        app.get('/unlink/facebook', function(req, res) {
            var user            = req.user;
            user.facebook.token = undefined;
            user.save(function(err) {
                res.redirect('/profile');
            });
        });

        // twitter --------------------------------
        app.get('/unlink/twitter', function(req, res) {
            var user           = req.user;
            user.twitter.token = undefined;
            user.save(function(err) {
               res.redirect('/profile');
            });
        });

        // google ---------------------------------
        app.get('/unlink/google', function(req, res) {
            var user          = req.user;
            user.google.token = undefined;
            user.save(function(err) {
               res.redirect('/profile');
            });
        });
    ...

In these routes, we just pull a user’s information out of the request (session) and then remove the correct information. Since we already had created our links to these routes in profile.ejs, they will now work since we have created the routes finally.

Now you can link an account and unlink an account.

When trying to unlink, we will have to do a little more configuration for that to work. Since the id is already stored in the database, we will have to plan for that scenario when a user links an account that was already previously linked.

Relinking Account After Unlinked

After a user is unlinked, their id still lives in the database. Therefore, when a user logs in or relinks an account, we have to check if their id exists in the database.

We will handle this in our Strategy. Let’s add to our Facebook Strategy.

config/passport.js

    ...
        // =========================================================================
        // FACEBOOK ================================================================
        // =========================================================================
        passport.use(new FacebookStrategy({

            // pull in our app id and secret from our auth.js file
            clientID        : configAuth.facebookAuth.clientID,
            clientSecret    : configAuth.facebookAuth.clientSecret,
            callbackURL     : configAuth.facebookAuth.callbackURL,
            passReqToCallback : true // allows us to pass in the req from our route (lets us check if a user is logged in or not)

        },

        // facebook will send back the token and profile
        function(req, token, refreshToken, profile, done) {

            // asynchronous
            process.nextTick(function() {

                // check if the user is already logged in
                if (!req.user) {

                    // find the user in the database based on their facebook id
                    User.findOne({ 'facebook.id' : profile.id }, function(err, user) {

                        // if there is an error, stop everything and return that
                        // ie an error connecting to the database
                        if (err)
                            return done(err);

                        // if the user is found, then log them in
                        if (user) {

                            // if there is a user id already but no token (user was linked at one point and then removed)
                            // just add our token and profile information
                            if (!user.facebook.token) {
                                user.facebook.token = token;
                                user.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName;
                                user.facebook.email = profile.emails[0].value;

                                user.save(function(err) {
                                    if (err)
                                        throw err;
                                    return done(null, user);
                                });
                            }

                            return done(null, user); // user found, return that user
                        } else {
                            // if there is no user found with that facebook id, create them
                            var newUser            = new User();

                            // set all of the facebook information in our user model
                            newUser.facebook.id    = profile.id; // set the users facebook id
                            newUser.facebook.token = token; // we will save the token that facebook provides to the user
                            newUser.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName; // look at the passport user profile to see how names are returned
                            newUser.facebook.email = profile.emails[0].value; // facebook can return multiple emails so we'll take the first

                            // save our user to the database
                            newUser.save(function(err) {
                                if (err)
                                    throw err;

                                // if successful, return the new user
                                return done(null, newUser);
                            });
                        }

                    });

                } else {
                    // user already exists and is logged in, we have to link accounts
                    var user            = req.user; // pull the user out of the session

                    // update the current users facebook credentials
                    user.facebook.id    = profile.id;
                    user.facebook.token = token;
                    user.facebook.name  = profile.name.givenName + ' ' + profile.name.familyName;
                    user.facebook.email = profile.emails[0].value;

                    // save the user
                    user.save(function(err) {
                        if (err)
                            throw err;
                        return done(null, user);
                    });
                }

            });

        }));
    ...

Now just add that same code across the board to all of our Strategies and we have an application that can register a user, link accounts, unlink accounts, and relink accounts.

Full Code

For those interested in seeing the entire code altogether, make sure you check out the GitHub repo. Also, here are direct links to the two most important files:

Conclusion

Hopefully, we covered most of the cases that you’ll run into when authenticating and authorizing users. Make sure to take a look at the full code and the demo to make sure that everything is working properly. If you see anything that raises questions, just let me know and be sure to go look at the full code for clarification!

Thanks for sticking with us throughout this entire series. We hope you enjoyed it. We’ll be expanding on authentication further in the future by doing a Node and Angular authentication tutorial. Until then, happy authenticating!

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