Retrieve Facebook User ID (or anything unique) without Authentication? - facebook

Is there anyway to get the Facebook ID of a user without forcing them to authenticate? I'm trying to create an app page where the user can only add an answer to a poll once, so I need to be able to identify viewers by some kind of unique identifier.
My preference would be to not force them to log in. I think it's bad UX to add 2 extra steps just so I can make sure a facebook user on a facebook page is unique. I don't need any permissions to their profile/etc.
BTW, I've seen similar questions though nothing current or close enough for me.

No possibility if you don't make your user log in, for security reasons, the user has to be aware you are collecting information about him, it's also why there is a login.
With the PHP SDK, to get the id after login:
$userId = $facebook->getUser();

Related

Facebook Registration versus Facebook Login, issue with username and saving user photo

I have a web app that has its own user registration, with a handful of users. The only mandatory fields are email, password and username, which must be unique. In the long run, I will still want to have our own registration system.
I would like to integrate Facebook, but I'm trying to figure out if I should integrate Facebook Registration or Facebook Login. I have these questions:
I've already started integrating Facebook Login and it works well. With this, not only can I enable Facebook users to login, but I can get all the information I need to register the user, if he is signing in for the first time via Facebook and has not registered via our site yet. I do not prompt the user for a password, to simplify the registration, however this means that if the user tries to sign in directly into our site, I tell the user that he must sign in via Facebook Login. Therefore, I question the need for Facebook Registration, which seems to be more complicated to integrate than Facebook Login. Can anyone tell me why I should integrate Facebook Registration instead?
The drawback I see with integrating Facebook Login or Facebook Registration into our existing user registration, is the username. I currently copy the user's Facebook username into our database. However, there is the possibility that the user's Facebook username is missing or is a duplicate of an username from one of our existing users, in which case I will have to prompt the user to change it. Then what happens if in the future, the user changes his username on Facebook? Should I change the user's username on our site when he logs in next via Facebook? What is best practices here? Am I correct to assume that if I don't bother changing the user's username on our site, it won't be an issue?
Then there is the possibility that the user's Facebook username is not valid by our requirements. Currently, we require the username to be alphanumeric and underscores only, using this reg expression: /^[\w]*$/ However, Facebook allows periods, but not consecutive special characters and possibly other criteria that I did not detect. This means that I should use the same validity check as Facebook uses. Does anyone know Facebook's reg expression for their usernames?
I am able to show the Facebook user's profile photo with an IMG tag and src= http://graph.facebook.com/facebook.id/picture. Does anyone know how to save the photo onto our server? We use Javascript and PHP.
Thanks for your help!
Hey I'll try to address your points 1 by 1
Facebook Login is merely a means to sign a user in to your site by them connecting via Facebook, as you state, they don't have a password as Facebook handles the auth. However you could redirect them to a specific page after using facebook login and get them to enter a password to use their account without being connected to facebook. The facebook registration plugin is more a tool to get users to register on your registration system (although it does support being your only registration system). It provides convenience by pre-populating a number of fields you might commonly ask for such as name etc. if a user is already logged in to Facebook. You can customise though to ask for additional info. It also means you can supply 1 registration form for your users whether or not they use facebook.
The facebook username should not be missing. Their 'name' field should be the users first and last name which I believe they have to supply. I don't think it can be empty. What I would actually suggest doing, is what I mentioned in point 1. Allow users to connect via facebook, but then prompt them to enter a username either as part of the login flow or after. You can then check this for uniqueness against your current database. To begin with you could assign them a username that is first_last_timestamp or something similar. This would more likely encourage them to change their username to something they want. If you used the registration plugin, you could easily enter your own "username" field into this. Then it doesn't matter if the user changes their name on facebook as they would still have a unique username to your site.
Facebook's usernames should just be a users first and last name (though obviously people do enter random things). The 'name' field is an combination of these so there will most likely be a space between them. You could always replace any invalid characters using your own regex, replace whitespace with underscores etc.
I'm not sure if there are any platform policies that would restrict you from saving the users picture to your own server/DB. What I would ask though is why you would want to? In my experience this is more likely to change then their name is. As such groups of friends using your site are probably more likely to recognise the profile pic that their friends use on facebook.
I would finally say, that the best bit about connecting their Facebook account either way means you can provide a smooth login experience so that a user doesn't have to sign in everytime. My own personal experience is that facebook login (with your own integration code on the success page) is better than the registration plugin. There are fewer steps for a user to connect to your app this way and they don't have to fill out a form. The success callback also means you can still perform the custom username code/flow I mentioned above and then prompt them to change their username if they desire. Just remember it is best to ask for as little info as possible at sign-up as users are more likely to join this way.
Hope this helps!

How do we use user access token to stay logged on to my FB canvas site even though another FB user is logged in through the original website?

My scenario is somewhat like this: A user logs into my website with his FB credentials. I capture his ID and the FB access token (say, a long-lived access token). He exits my website, and returns back later. However, this time, his browser has FB open with a different ID. Would I be able to load facebook details of this old id (with which he had registered on my site) using the stored access tokens? Is it possible, or would it result in a clash between the old and the existing FB id?
Correct me if I'm wrong, but he/she should stay logged into your website, regaurdless if his authID changes.
First of all, why would you want to do that? Since Facebook does not allow multiple user accounts for one and the same person, the only case where this would normally come into play is when another user is using my computer/browser – and why would I want you to read my info while that other person is using my device …?
Second of all, as long as the first user is still considered logged in to your site, it makes not much difference. But lets say some client-side method is called that updates the cookie information, then that’s where trouble might start. You might still be able to read the old user’s info, since you have his valid access token – but you’d have to use that token in your requests explicitly, and also address the account specifically, since the Graph API’s /me would point to the new user.
But as I said, I can hardly imagine a real, practical use case here …

facebook register/login

I'm trying to implement facebook connect to my website, and i have couple questions.
1: Is it possible to register user in my website using his current facebook email/password.
Let's say user clicks on link Register via facebook and then he have to give me permisions to access his password, email, etc... and after that is done i put that info in my own database and he will be able to login with that account any time he wants without needing to give me permisions any time in the future.
2: If that kind of registration is not possible, what's other solution would be the best for me? Because i need to somehow keep track of that user who logged in with facebook, because he can upload photos, send messages etc.
Anyways, i'm quite new with facebook and similar things, so i'm really lost here, hope some one can help me :)
EDIT Thank you all for wonderful answers it helped me a lot, now all that's left is to read documentation :)
Yes it is, it is possible to get the information of the user. But it is rather complicated, when you have never dealt with it.
First you need to send the user to the following link:
https://m.facebook.com/dialog/oauth?client_id=your-client-id&redirect_uri=xxx&scope=listof-information-you-want
Facebook will then return your client to the uri specified, if the user rejected it will give a reason. If it is not you will get an code in urlencoded format.
This code is needed for the following step, the request of the access token:
https://graph.facebook.com/oauth/access_token?redirect_uri=xxx&client_id=xxx&client_secret=xxx&code=xxxx
This will give back an access token, if the authorization didn't fail.
After that you can ask for the information you want:
https://graph.facebook.com/me?method=GET&metadata=true&format=json&access_token=access_token
This will include a facebook uid, which is unique for all users. Store it and you can discern between a register and login.
This is roughly the process for any oauth2 application.
Facebook will not ask repeatedly for permissions after the user granted them to you. So you can store the access token and reuse it for backend stuff and also use the same procedure you use for register for login.
You can never access the user's password from Facebook even with his/her permission, so the user will always have to authenticate via Facebook and have Facebook pass you the user id of the logged in user once authentication succeeds. You can store all kinds of other data locally, but not enough to authenticate the user yourself.
Once the user is authenticated, you'll have access to the user's Facebook user id via the API, which should be enough to connect all kinds of information to that specific user.
Facebook does not provide access to accounts when passwords are taken from your controls. It provides it own canvas for login information. Therefore you cannot use your first approach to store passwords in your databases. Check this out.
You can however store email addresses once user logins into his account using the facebook sdks. Check this out link for the example of C# SDK sample code.
You can use the Facebook APIs to fetch user email-id, photos, friendslist and other information and then play around accordingly.
You don't get access to the users password - only email if you ask for it.
Best way would be to have a table of users and their Facebook account id's.
If you want to allow users to sign up without Facebook then have a nullable field for their password and facebook id, and also have a field for username - which you could populate from Facebook if they register via that route.

Facebook app without prompted authentication

I've been trying to figure out a way to have my iframe Facebook app (built in PHP) work without requiring separate authentication methods. I am already logged into Facebook, but for some reason I still see all these Oauth notices from the example in the PHP SDK.
The only data I need is publicly available even without them "adding" my app. I am looking to collect their Facebook ID (since this is a contest, we need a unique ID for tracking), their name and (optionally) their email address as well.
The problem is, I cannot use the API to fetch the public information unless I already know their Facebook username. Any ideas on how I might be able to get their logged-in username or public handle so I can then fetch the rest of the information?
For whatever reason, Oauth is driving me completely insane with Facebook today.
Sidenote:
I did manage to technically get the Javascript SDK operational, which fed some information to PHP for use. The only issue there is that once I login, I don't see the data. If I refresh...then it shows up. Unsure why the refresh is required, as I wouldn't expect a user to actually have to hit refresh in order to proceed with the app.
I guess you are a bit confused here, Facebook will NOT share the username, id, full name or email without the user explicitly authorizing/allowing your application (and in the case of the email, requesting the email permission!).
Read the official Canvas Tutorial for more information:
In order to gain access to all the user information available to your
app by default (like the user's Facebook ID), the user must authorize
your app.

username conflicts when allowing users to log in via facebook

I would like to allow visitors to my website to log in using Facebook as opposed to requiring them to register - which is accomplished easily enough with the information here:
https://developers.facebook.com/docs/guides/web/
However, I would also like to keep the option of registration open. In other words, when a user first visits, he has the option of either registering with me, OR simply logging in using facebook. A profile on my site is then created for them, and everything is wonderful.
My thoughts are, for facebookers, to use their facebook username. However, this might cause issues when someone whose facebook username is "foo" visits for the first time and logs in using facebook, if somebody else has already registered with the username "foo".
Has anybody else run into this issue? What's the best way to mitigate it? Should I just use facebook registration instead?
I randomly generate a username (UUID, actually) when they login using alternate auth (Facebook, Twitter or OpenID). You can then allow them to choose a username at a later point from a profile page.
If you want, you can flag auto-generated usernames, so they won't display, which would be confusing.
I also use the same process, but reversed, to allow logged in users to match up an external account when already logged in.