Exercise (Video): Using OAuth with Passport and Facebook

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Server-side Development with NodeJS, Express and MongoDB

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The Hong Kong University of Science and Technology

Server-side Development with NodeJS, Express and MongoDB

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Course 4 of 4 in the Specialization Full-Stack Web Development with React

This course deals with all things server-side. We base the entire course around the NodeJS platform. We start with a brief overview of the Web protocols: HTTP and HTTPS. We examine NodeJS and NodeJS modules: Express for building web servers. On the database side, we review basic CRUD operations, NoSQL databases, in particular MongoDB and Mongoose for accessing MongoDB from NodeJS. We examine the REST concepts and building a RESTful API. We touch upon authentication and security. Finally we review backend as a service (BaaS) approaches, including mobile BaaS, both open-source and commercial BaaS services. At the end of this course, you will be able to: - Demonstrate an understanding of server-side concepts, CRUD and REST - Build and configure a backend server using NodeJS framework - Build a RESTful API for the front-end to access backend services

From the lesson

Backend as a Service (BaaS)

In this module we learn about Mongoose population, a way of cross-referencing documents and populating the documents from other documents. We then review secure communication using HTTPS. We look at Backend as a Service (BaaS) and take a brief look at Loopback.

OAuth and User Authentication25:43

Exercise (Video): Using OAuth with Passport and Facebook36:35

Meet the Instructors

Jogesh K. Muppala
Associate Professor
Department of Computer Science and Engineering

[MUSIC]

Now that we have understood about OAuth 2 and how Facebook supports OAuth 2,

let's move onto this exercise where we will configure our express server

application to make use of Facebook as the OAuth 2 provider for our server.

And at the same time for our client application.

In this exercise we're going to be relying on the passport that

we have already configured in our express application.

We will configure a new strategy for authenticating with Facebook

using that passport Facebook token node module.

To get started on this exercise,

go to https//developers.facebook.com/apps.

Now, this is where you will register the client application, which is basically

your server, the extra server, acting as the client application for Facebook.

And then we will register a client application there.

And then get hold of an app ID and an app secret from Facebook.

Now obviously it goes without saying that you need to have a Facebook account

in order to be able to configure this.

If you don't have a Facebook account and you do not wish to do this exercise,

then there is no harm in not doing this exercise.

But of course for doing this OAuth 2 exercise,

you need a Facebook account to configure your OAuth provider on Facebook.

So going to this site,

developers.Facebook.com/apps, you will notice that you will need

to login in order to continue if you are not logged in from your browser.

Now you can see that I have already configured a few apps here and

tested them out.

Now, to create a new app click on the Add New App.

And then you can provide the name for your app.

So I can say Confusion3, and then we can provide the contact email.

And then follow the procedure to create your new app here.

And once the app is created, you will immediately notice that

there is an app ID that has been created for your app.

And then for this particular app.

So if you're going to the dashboard, you will see

two pieces of information that you really require in order to proceed further.

One is the App ID, so make sure that you make a copy of the App ID.

And the second one is the app secret.

So, you can type on the show button here and then you'll get the app secret.

Secret here so as you can see these two are nothing but ASCII strings.

So make a copy of this because you need to configure your expert server and

also your client application with these two pieces of information.

And once you get hold of that then

we can proceed ahead with the rest of the exercise.

You'll need to go to your dashboard of your application.

And in the settings, as you can see, in the basic settings here

you just add a website platform here.

And then supply the URL as https//localhost3443.

And save the changes here to your application here.

After adding in the website here go to the advanced settings.

And then click on Yes to say native or

desktop app here and say yes to that and then save the changes.

And in the basic setting in the app domains, type in

https://localhost:3443 and save the changes.

Next, go to the exercise instructions for this exercise.

And you would see that there is an index.html file that

I have provided in the exercise resources.

Download this index.html file, and then move it into your public folder.

So let's download this index.html file.

Next, going to the conFusionServer folder in the public folder,

you see that I already have an index.html file.

I'm going to replace this with the downloaded index.html file

that I just obtained.

I have saved this on my desktop.

So I'm just going to pull this index.html and

then replace the index.html file in the public folder of my conFusionServer.

Next, going to the editor, let's open the index.html file.

And if you open it you will see that I have already configured some JavaScript

code here.

This JavaScript code I got hold of from Facebook where they

specify how you can configure a Dev application using this.

So, I have copied this from the Facebook instructions.

In particular you will notice that in this index.html file,

there is this appId field here.

You're going to be replacing this appId field with the client

Id that you obtained by registering your app on Facebook.

So, here, I am replacing this client's Id

with the Id of my app that I have registered on Facebook here.

And you need to do the same step with the app

that you register on Facebook, with the app ID that you get from Facebook.

And then save the changes to index.html.

This index.html page that I have here will create

a login button on the index.html page, which when clicked will

Help us to login to Facebook and then obtain an access token from Facebook.

Next, going to the conFusionServer folder,

we will install the passport Facebook token node module.

So at the prompt type npm install

Passport-facebook-token and

install this node module.

And as you can see I am using the 3.3.0 version in this course.

Going back to the editor, open config.js.

And in config.js I'm going to add in

a Property called 'facebook' into my config.js file.

And inside here, I will

configure my clientId and

the clientSecret.

Now, the clientId will be exactly what you obtain from Facebook.

Here, and the client's secret as you saw when you registered your application.

You get a second string there so copy that string and

then paste it into the ClientSecret here.

Now make sure that this is pasted as a string here.

Similarly, pasting in the ClientSecret into my config.js file.

So, configuring this here will help me to use these two where I need in my code.

Next, as we realized, whenever the user

logs in and then obtains the access token and passes it on to our express server.

The express server is going to use that access token and go and

fetch the file information from the Facebook 0 ought server.

And then, once it attains the profile information, then our express server will

create a new user account into our application.

And use the Facebook ID as the index into this use account.

So to accommodate this,

we will go into the user.js file where we have define our model.

So in addition to the first name and the last name,

I will also add in a field here called facebookId,

which is of the type String here.

The facebookId will store the facebookId of

the user that has passed in the access token.

In the next step I will show you how to configure this.

Then we configure our Facebook strategy using the passport Facebook token..

When a user passes in the access token,

then you're going to be fetching the profile and then setting up an account for

that user in our local server here, in our express server here.

We will be initializing the first name and the last name and the facebookId.

But of course this particular account will not have a password or

rather the hash installed associated with this.

Because, if a user makes login using this account then they will have to use their

Facebook login part in order to login to our application.

Next we will go to authenticate dark.js file.

So this where we have been setting up all our different passport

authentication strategies.

So here in addition to the jwt strategy and

the local strategy that I have configured here,

let me create a FacebookTokenStrategy here.

And then set the require password-facebook-token.

And this will give us a new strategy that we can

configure in our passport module here.

So, going down into the code here, right there,

at the end of this file, I will create,

facebookPassport as

passsport.use().

And so this is where I would specify new FacebookTokenStrategy here.

And then we will specify the details of this

FacebookTokenStrategy, right at this point here.

So, in this FacebookTokenStrategy, how do we approach this problem?

Let me just wrap around the word wrap so that you can see the complete code.

So for the FacebookTokenStrategy, we will start up by saying first.

The first part of the FacebookTokenStrategy takes the clientId.

Which we have config at config.facebook.clientId here,

and client, Secret,

which also we have configured in, Our config file here.

So we're going to be supplying this as the first parameter to this strategy here.

And then the second parameter, is where the defying

the callback function that comes in at this point.

So the callback function here gets three values.

So it gets accessToken,

refreshToken, profile, and

callback called as done here.

So these are the four parameters that come into the callback function that we will

configure at this point.

So let me indent that code in so that it's a bit more clearer to see.

And inside this callback function that I configure here,

I'm going to first say User.findOne.

So we'll try to see if this particular Facebook user

has logged in earlier so the account would already

be configured, With the facebookId.

Now where do we obtain the facebookId?

Notice that we're getting that profile for the user,

coming in here, so you can see that this profile is coming in as a parameter.

This profile will carry a lot of information coming from Facebook that we

can use within our application.

The accessToken, of course, is supplied to the server by the user.

So, once we try and find at least one user with a Facebook profile id.

So if this user exists then we have already found that the user has previously

logged into our account using the Facebook approach.

So, in this case we can proceed forward otherwise we will create a new user.

So, the callback function here there will have two parameters,

the err and the user here.

And this callback function as we will see,

well inside here we will check to see if (err).

So if this causes an error, then of course

what we need to do is return done(err, false).

So this done as you can see is the callback function that is coming in as

the parameter to this function here, so

we'll call the done with the err and false.

If it is not an error then

we'll say if (!err

&& user !== null).

So if the user is not null, so that means that we have found a user in the system

that has not been earlier with that particular facebookId, So for the user,

all that we need to do is return done(null, ) since

there is no error here, and then we'll return the user value for this down here.

So which means that if the user has already logged in earlier using

the Facebook approach, then the user would have already been created.

And so, that user will be found and then we just pass back that user.

If not, see the if not part is the more interesting part of this exercise.

If the user doesn't exist, then we need to create a new user.

Now to create the new user, we will say user,

= new User, and when we create a new user,

recall that we need to pass in the username.

The username would be obtained from the profile, and the Facebook profile that

has returned will have a field called as a displayName.

And so that is the field that I'm going to use to create a new user here.

So we will create a new user with the username set

equal to the displayName, and after the user is created,

then we will say user.facebookId, = profile.id.

So we're going to be saving the Facebook ID of the user.

So return in this profile object here, and

then put the user's Facebook ID to the profile ID.

So that subsequently, if the same user logs in,

this search will be able to find this user in our database.

And then we will

say user.firstname

= profile.name.givenName

So the profile has this name object on it,

which has a given name and a family name associated with this.

This is returned from the user's Facebook profile.

And also the user.lastname we will set

it to profile.name.familyName.

And then, once we have set up all of these we will say user.save.

So we're saving the changes to the user and

then this will return err and the user.

So, it will return an error if the user could not be created,

otherwise it will return the created user here.

So in this case we'll say, if (err),

then will return done (err,

false) because we didn't manage to create the user.

else, the user was successfully created,

so we'll return done(null, user).

So no matter what the case is,

if the user exists then you will find that user and return the value.

If the user doesn't exist you're going to be creating a new user based upon

the user's Facebook profile that we obtained.

And then add in the new user into our server site, into the database.

So this is the strategy that we configure for

our passport, the new FacebookTokenStrategy.

So this will enable us to find the user.

So now that we have configured our application to either

create a user or find the user based on the Facebook ID.

The last step is of course to introduce

a new route into the users.js file.

So in the users.js file you'll recall that we had the sign up route which

allows the user to sign up for local account with the user name and password.

And then you have the login which allows the user to log in using the username and

password.

But now, we're going to be using Facebook for logging in the user.

So in this case we will say, router.get,

and the endpoint will be /facebook/token.

So if the user sends a get request to users/facebook/token,

then we're going to be authenticating the user using

the Facebook OAuth 2 based authentication.

So here, we will say passport.authenticate, and

we're going to be authenticating using the facebook-token strategy.

Recall that we had already configured this in our authenticate.js file,

so we'll configure the passport authenticate facebook-token strategy and

then that callback function which gets req, res here.

So let me, Toggle the word wrap here,

so you can see that this is the router.get on this endpoint here.

And then in here, I will configure this application.

So, at this point, we would say, if (req.user), now notice that when we call

passport.authenticate with the facebook-token strategy.

This, if it is successful,

it would have loaded in the user into the request object.

So by the time we come to this point here after the passport.authenticate

facebook-token middle ware is executed,

you would have the user already loaded into the request object.

So if this is the case, Then, we'll say, we'll create a token.

We will create a JSON web token here, just like the way we

created the JSON web token when the user logged in here.

So, we're going to be copying that here.

Authenticate.getToken, so this will get us the JSON web token.

So essentially, the user is sending the access token to the express server,

the express server uses the accessToken to go to Facebook and

then fetch the profile of the user.

And if the user doesn't exist, we'll create a new user with that Facebook ID.

And then after that, then our express server will generate

a JSON web token and then return the JSON web token to our client.

All subsequent accesses from our user will have to include this JSON

web token that we have just returned by using this approach.

So at this point you no longer need the Facebook access token anymore.

You can discard the Facebook access token at this point because

the JSON web token is the one that keeps the users authentication active for

whatever duration that this JSON web token is active.

Now in addition to this, of course we also need to do these steps here.

So I'm just going to copy that part here.

because I'm going to do exactly the same thing in this case also,

so we will paste in that code here.

So we'll say statusCode = 200, content header type, and

then we'll say res.json you're successfully logged in, and that's it.

So with this approach, as you can see, now using a call to this endpoint.

The user application, the client in this case,

will pass in the Facebook access token that it has just obtained from Facebook.

And then our express server will then use the Facebook access token to

verify the user on Facebook.

And then if the user is acknowledged by Facebook to be a legitimate user,

then our express server will return a JSON wed token to our client.

And then our client is authenticated and

then can proceed forward with carrying out the other operations

using the JSON wed token in the header of all the request messages.

Subsequently, just like we did with the local authentication strategy, that's it.

So we have completed all the updates to our application, let's save the changes.

Going to our terminal, let's start up the server here,

so we'll say npm start, and the server is up and running.

And I noticed that I had typed in P-A-S-S-S port,

and so this caused an error here.

So notice that how easy it is to make errors.

So let me go and correct that and then come back and restart my server.

So, when you encounter errors like these, don't panic.

Look around to see where the problem is and very often,

it will be a simple problem like this that will cause errors for you.

Again, going back to the users.js and

you see that in the authenticate.js file,

I have configured this saying P-A-S-S-S port.

So in the authenticate.js file, let me fix that to passsport and

then save the changes and then restart my server.

Now, restarting my server, So my server is now up and running.

At this point, go to a browser.

And in the browser, type https://localhost3443.

If you happen to have this page cached here, you may wish to remove the cache.

Or just type localhost:3343/index.html, and

then you will immediately notice that in this index.html,

you will see this button called Log In button.

So we're going to click on this login button to login to Facebook.

Let's log in and then you will come up with this message here.

Which if you have already logged in to Facebook earlier,

it'll ask for the permission to continue as the user.

If not, then it'll ask you to log in to Facebook with and

then allow you to continue.

Since I had just logged in to Facebook a little bit earlier, so

I can just click on Continue.

Now, open the developers JavaScript console at the bottom here.

And in the JavaScript console, you see a bunch of messages printed in here.

And then in particular,

open this object that you will see in the JavaScript console.

And inside this object, you will see this alt response here.

And in there, you will see an access tool present there.

Now, this is a reply that is obtained from Facebook or

out to authentication server by our application here.

And I'm going to simply copy this,

because this is the access token that Facebook has supplied to us.

Now, I need to give this access token to my express server in order for

it to go and verify my profile, and then allow me to log in to that application.

So I am doing this in a clenched way

here simply because I wanted to show you how the access token comes in here.

And we copy the access token, then I'm going to take this and

use Postman to send this access token to my Express server.

Now, when you design a web app like Angular, or

the Ionic app, or the NativeScript app, you don't need to do all these steps.

Now, basically when the access token is returned to your web app,

the Angular app, or the Ionic app, or the NativeScript app,

you'll simply capture this access token in there.

And then you will pass this access token on to the Express

server using the XMLHttpRequest to obtain the information.

But since I wanted to manually illustrate the steps.

So, I set up this index.html with a simple JavaScript

code that Facebook provides for me.

So that I will be able to retrieve this authorization token that we obtained from

Facebook.

So let me copy this authorization token.

Now, we will go to Postman, and then try and

see how we can obtain the JSON web token from our Express server.

Now, going to Postman, from Postman,

let me now do a GET request to

localhost:3443User'sFacebooktoken.

And when I send this request to that point,

the other configuration that I need to do here is that,

I need to pass in this access token that I have just obtained.

Now, to pass an access token in the header,

I can pass it in as an authorization header by typing authorization.

But note that the value should be typed as Beta with a capital B in this case,

and then paste that access token that we obtained from Facebook in here.

Note the capital B here, and

then you can pass in this to our server.

And then upon reply from our server,

you would see that you would have obtained the JSON web token from our server site.

So this is one way that you obtain the JSON web token by exchanging your

access token from Facebook that you have just obtained with your Express server.

And your Express server in turn will go and

obtain your profile information from Facebook, and

then create an account specifically for you, and

then return you the JSON web token if everything is successful.

Another way of passing in this information is in the header,

you type access_token as the key.

And in the value, you just type in the access

token like this here, and then you can send the request And the same thing.

It'll again return the JSON web token for you.

And then you'd capture the JSON web token, and then carry on with the rest

of the accesses to your express server using this JSON web token.

A third approach is to include this into

your URL itself as a query parameter.

The third approach is to say token?access_token= and

then paste the JSON web token into that query parameter.

Don't use the quotes here, just the JSON web token itself.

And then send the request to your server.

And then even then your server will return the corresponding JSON web token.

So you see three different ways that you can parse in your Facebook Access Token to

your server, and then obtain the JSON web token from your server.

And after this, the rest of these steps proceed just like before.

Now to convince you that actually a new account has been created with the Facebook

profile for this particular user, let's go to the terminal.

In the terminal, in a new terminal window, I will start the mongo ripple here.

So in the mongo ripple, let me say, use conFusion.

And then I'll say, db.users.find().pretty(),

and then print out all the users that are registered in my system.

You notice that the three users that we had configured in the previous exercises

are all there.

Notice in addition a fourth user that has just been added in.

And note that for this particular user, we don't have the hash in source yet,

but instead the facebookId of that user is set up, and

the username is set up to be that value, and the firstname is set up there.

And also the last name should have been set up here but

I think there's a small error in my code.

So I will go and check the lastname part of it there.

Going to authenticate.js.

Let me see if I made mistake here.

There we go.

I typed in F-A-M-I-L-Y Name.

So you see, even I am not about making mistakes.

So this should be familyName here,

user.lastname profile.name.familyName here.

So let me save the changes, and now the code should work correctly.

Again going back to the terminal,

you now see that a new user has been created with the Facebook profile here.

Now any subsequent time I tried to authenticate myself using Facebook

is the same process.

I obtained the access token from Facebook and

then parse in the access token to my express server.

My express server will then go to Facebook, fetch the profile and

then check to see if the user already exists.

And in the subsequent login that I do using Facebook,

I would find that this particular user is already existing in the system.

So, it'll simply proceed forward and the user will be authenticated and

then the extra server will issue a JSON web token to their

client and we can proceed forward from that point onwards just like before.

So you see, setting up OAuth 2 based authentication using a OAuth

2 service provider like Facebook is not that difficult provided we get hold

of the appropriate passport Facebook authentication strategy based module.

Like passport Facebook token which already takes care of much of

the work on our behalf and then enables us to set up our express server

to handle third party authentication based on OAuth 2 from Facebook.

With this, we complete this exercise.

In this exercise, we have learned how to do all OAuth 2 authentication

using Facebook as the OAuth 2 authentication provided.

This is a good time for you to save the changes that you've made to

your Git Repository with the message passport Facebook.

[MUSIC]

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