Facebook Graph API: Reuse the code verification string? - facebook

The authorization section of this page developers.facebook.com / docs / api contains a good description on how to perform authentication for a user agains my Facebook app. However, in my scenario I cannot get it to work the way I want. Here is how it is supposed to work:
User comes to my login page and clicks a "Sign in with Facebook" link.
User gets redirected to graph.facebook.com / oauth /authorize?[some params] and authorizes my Facebook app to access his/her data. Facebook redirects back to my site.
My site checks the Code parameter, calls Facebook to replace it for an access token, and then lets the user connect his/her account on my site with the account on Facebook. The access token is saved on the user account on my site.
The next time user arrives at my site and want to login, he/she should be able to click the same "Sign in with Facebook" link and directly get signed in with the site account (assuming he/she is still logged into Facebook)
Problem: Each time the code (from graph.facebook.com / oauth/authorize) is replaced for an access token, the token is changed. Since that token is used to look up the user in my site database, the matching failes.
My question is now: How do I solve this problem? Can the Code parameter from graph.facebook.com /oauth/authorize be saved and used over and over again to look up user? Or is there another way to do this? I really would prefer NOT using the Javascript API since it gives me lots of other troubles.
[Sorry about the links, I am a new user and not allowed to post more than one link]

Ah, I solved it: After I got the access_token I just call graph.facebook.com/me to get the id of the user. This is saved to my database. Next time I match against that id.

Related

Auto Posting to Multiple Facebook Pages using Graph API - Auth Issues

I am pulling my hair out trying to understand what Facebook wants me to do to post to a FaceBook Page as a System User that has Admin and Page Privileges to and Owned by our business (We have Facebook Business Manager).
In a nut shell all I want to do is make this call:
https://graph.facebook.com/v2.5/${MyPageID}/feed
What I don't get is the access_token part.
I can generate access tokes for Apps, for Pages but all result in 403 returned from FaceBook. I have gone as far and checking every box available on the generate access token popup on the graph api and still I get 403 "Forbidden" so I am detailing the little I understand of the insanity that is FaceBook Auth in the hope that someone can explain where I am going wrong.
1) To Post as a System User to a Page I have to Create a FB App (I Would prefer just to post direct to the pages and skip the App part, My System User has Admin Access on All pages)
2) To Access the App I need an App Token.
3) To Create an App token I need a User Token.
4) To Create a user token I need to log in to Facebook and have all sorts of permissions on the App. (I can't log in as the System User! FB asks me to login as myself. I am not sure if this breaks the Auth Token generated?)
5) Then there are all sorts of swapping tokens to get a Permanent App token, Another point of potential failure!
6) IF the stars and moon align and you stand on your head the permanent App key can be passed to the above call as the access_token
I don't understand how to link the Pages I want to post to with the App created. Do I have to have 1 App for Each Page?
I have got one page to work, We initially used that App to Auth against the Instant Article Graph API:
https://graph.facebook.com/v2.5/${MyPageID}/instant_articles
I could not use the above token for the /feed url, I had to generate a new token with extra publish permissions and the page published with no problems, however when I change the ${MyPageID} to another page using the same access_token I get the 403.
I tried Creating a new App, I have no clue how they link to a specific page So the App to me seems sort of redundant.
Any help with what I am doing wrong or how I can go about simply posting to various FB Pages with a System User using the /feed api ?
The calls are made form a Spring Boot Java APP using HTTP Posts.
How to get a System User Auth and Page Auth:
1) Generate a User Token for an App (Button above the System User):
https://business.facebook.com/settings/system-users/${System User ID}?business_id=${your_business_manager_id}
System user has Page Admin on each page you need to post to.
App is just an FB app, not sure what it does other that it is a grouping I generate a token against.
I chose: (manage_pages, publish_pages, publish_actions, pages_manage_instant_articles, pages_show_list)
2) Check your access token:
https://developers.facebook.com/tools/debug/accesstoken/?access_token=${The access token you got from the step above}&version=v2.12
This will provide you with the App ID the Token is for and how long it lasts (we need a Permanent token)
3) Using Graph API Explorer gets the Accounts this token has access to:
https://developers.facebook.com/tools/explorer/${Your FB APP ID}/?method=GET&path=me%2Faccounts&version=v2.12
4) Using the output above find Page Auth for each page you wan to publish to
5) Post to each page in turn:
https://graph.facebook.com/v2.5/${MyPageID}/feed

Is code parameter Value means access_token after Facebook OAuth to my website

I had made a Facebook APP for authorization of users on my Website, I am using OAuth Method. In My Site i have kept a Feature called "Login in With Facebook", when user clicks he gets redirected to Facebook with link
https://www.facebook.com/v2.2/dialog/oauth?client_id=<ID>&redirect_uri=<mysite>&state=<some random hash>&scope=
This looks fine enough, Now Facebook asks for Allow and when Users clicks allow, I get a URL Back on my site with a Special parameter called &code= .. It looks like
http://mywebsite.com/facebook&code=<some huge Random code>&state=<hash>
Now, i would like to know what exactly is code= parameter value says, is it the access Token of the User because i don't see special parameters like access_token=. So can somebody tell me what is code means in OAuth and is it same as Access token. ?? How can i verify it.. Please input your thoughts
Your app needs to exchange that code server-side for an access_token
There's specific documentation for this flow but essentially you take the code, your app ID, app secret, and the redirect_uri you used when opening the dialog initially, and make an API call to exchange the code for an access token
You then use the access token to make API calls on behalf of the user

Posting to a Facebook Page Wall from a Web Server

I've been reading documentation and Stack Overflow link all morning, but I'm just not understanding the correct process to authorize a web server to post to a Facebook page wall.
What I'm not clear on is why I have to post to Facebook as a Facebook User, using an access_token, meaning that this user has to log into Facebook manually to authorize my app.
I'm not trying to authorize a User, nor any of my visitors to do anything with their accounts, so I don't need any permissions from them. Instead, I'm trying to authorize my Web Server to post updates to its wall as a specific Page.
Why do I have to use a user access_token to do this? I'm not attempting to impersonate the user, I'm trying to post to the page as the page...
Is it possible to authorize a user and get their access token without having to create a login page on the Web Server? I don't want to have to require the user to login to make this work, I thought that was the point of having an app ID and Secret?
I guess my question is this: Is it not possible to allow a web server to post to a Facebook page wall as that page, without having to present a login dialog to a specific user? If it is possible, what is the correct workflow to set this up?
In order to post to a Page as a Page, you have to use a Page Access Token. You get that with a User Access Token, and you can extend it so it will stay valid forever.
Steps:
Request a User Access Token with the manage_pages permission (valid for up to 2 hours)
Extend the User Access Token (valid for up to 60 days)
Get the Extended Page Access Token for your Page with the User Session
Store and User The Page Access Token in the publish call
It may sound a bit complicated, but there are many tutorials for this and you don´t actually need to program it, you can just use the Graph API Explorer.
Here are some Links about the Access Tokens:
https://developers.facebook.com/docs/facebook-login/access-tokens/
http://www.devils-heaven.com/facebook-access-tokens/ (see "Extended Page Access Token" for a step by step tutorial)

Facebook with dotnetopenauth

I have created an App on facebook and I am using this app to authorize an user via dotnetopenauth.
Here I would pass APPID and APPSECRET and get the token which would be used to call Facebook Graph to get facebook user details.
If I'm doing this for the first time, user would be asked to enter username/passowrd on the Facebook website and then the session is created in the browser and it will redirect to my website as a Facebook user. This means that if I open a new tab in the current window and open facebook, user will see his/her page directly without asking for username/password. - this is obvious and understandable.
// code
request = WebRequest.Create("https://graph.facebook.com/me?access_token=" + Uri.EscapeDataString(strAccessToken));
response = request.GetResponse();
My query is:
After the scenario above, if user logs out from Facebook website OR I close the browser window, the facebook session is lost. However, I still have the access token (string in the above code) that I got while authenticating.
So, As of this moment I am not storing any user information from Facebook (not even cookies or anything else). I am just requesting user to authorize my application as a Facebook user. When user does that, I get the access token which I can use it to make calls to Graph and REST APIs. This access token usually remains same, so I really dont need to pass the applicaition id and secret to get the token next time onwards. Actually I can request the graph APIs and REST APIs with the stored token and request user details. I have tested this and works fine.
What I am looking for is, if user opens www.facebook.com, user should see his/her personal facebook page which obviosuly is possible only if I have a session in the current browser. Hence, my question was: how do I use my access token OR what call should I make with my access token so that I can set the browser session for the facebook user? Is it possible technically?
Regards,
AG
No. Your access token is used by your web server to call facebook. It's impossible (and undesirable) for this to impact the user's browser in a way that would set a facebook.com cookie so that the user would be implicitly logged into Facebook by your use of the access token.

how to make "uploaded via" link at the bottom of the post to link to user's website?

what I need: upload photos to user's fan page as a page, using an app for that
what I have: my website which does uploading, and a user, who created fan page and application, and that app's id and secret
what I do:
call FB.init() with that appId
call FB.login() with manage_pages,publish_stream permissions - this prompts FB login popup where user is asked to login and then to authenticate the app. As the result I get app access token.
Send request to https://graph.facebook.com/oauth/access_token?client_id=APP_ID&client_secret=APP_SECRET&grant_type=fb_exchange_token&fb_exchange_token=TOKEN_FROM_ABOVE to get extended app token valid for 2 months (and therefore page tokens will be extended as well as described here)
Send request to https://graph.facebook.com/me/accounts?access_token=TOKEN_FROM_ABOVE to get a list of pages user manages, and let user to choose the page he wants to publish to.
That gives me PAGE access token I can use to publish photos to user's FAN page using /albumId/photos/ API call.
what is the problem:
the "via" link in the photo redirects user to MY website (where user has authenticated his app to upload to his page):
that is because I had to ask user to enter my website's URL in app settings, otherwise Facebook login dialog will complain:
SO MY QUESTIONS ARE:
Am I doing this right? am I missing something probably?
If I am - then how can I get that "via" link to link to user's website?
Thank you.
how can I get that "via" link to link to user's website?
Not at all, because this always links to the app that was used making a post/upload.
What you could try though is having your website redirect when a user is coming to your site from Facebook. Which post/feed story the user is coming from should be passed to your site as parameters; then you’d only have to figure out which user made that post (look it up in your database), and redirect to their homepage.
I ended up adding client's website URL as a query string parameter into "Site URL" field in the application settings - and then I need to modify my site's backend to do redirects:
http://mysite.com/?redirect=http://client-site.com