APP_ID

APP_SECRET

ACCESS_TOKEN

Access token (short-lived or long-lived) obtained through Authorization Flow

POST_ID

TIMESTAMP

INPUT_TOKEN

Access token (short-lived or long-lived) associated with YOU, the Facebook App owner

OWNER_ACCESS_TOKEN

Owner's access token (short-lived or long-lived) obtained

CREATED_TIME

Facebook’s Graph API is the central means for programmatic access to Facebook data.  It is the entry point for reading and writing to Facebook’s “social graph”. 

This course begins with a discussion of the major concepts of the Facebook Graph API. You will learn basic concepts like authentication, authorization, and access tokens. Then, you will build out your mini-project step by step by deploying the "Login with Facebook"  web page. By the end, you will have a thorough understanding of how to build API integrations in your own projects.

Facebook Login and the Facebook Graph API

## A note about the `/friends` edge

By this point, you should be feeling pretty familiar and confident with navigating around the Graph API. You certainly have a great foundation for further self-learning!

Let's make a quick point about the `friends` edge, which is located at `/{user-id}/friends` (or `/me/friends`). Chances are, you will be eager to use this endpoint as you play around.

Let's try it out here with your test user:

curl -X GET -H "Authorization: Bearer {{ACCESS_TOKEN}}" \
"https://graph.facebook.com/v10.0/me/friends" \
| json_pp

Shell-curl

As you ran the above query, you may have noticed a few things:

* The response had a `summary` with a `total_count`, which included the number of friends that this test user has. Do you remember when you were setting up test users you made some of your test users _friends_ with other test users?
* But even if your `total_count` is a number like 2 or 3 (for example) the `data` part of the response might be an empty `[]` array or array with _one_ element.


Where is the data for these friends? If your test user has 3 friends, why is `data` empty or containing only one element?

Facebook's documentation for the friends' endpoint makes this clear:

> Only friends who have installed the app and who have granted the app the `user_friends` permission will be included. 


Remember, when creating test users, there was one test user already created by default (say `user xyz`). If the `user xyz` is friends with the test user, you will be seeing it in the `data` array. Because for `user xyz`, `user_friends` permission is included by default, and you don't need to authorize it separately. If by any chance no test user was created by default, your `data` would be empty. 

In the case of test users which you created manually, it is not enough for `test user 1` to be friends with `test user 2`. Sure, that relationship will affect the `total_count` of friends for `test user 1`, but `test user 2` also needs to _authorize its application_ to see the friends for `test user 1`.

To verify this, do the following:

1. In another tab, log out of Facebook.

2. Run the same React app with the 'Login with Facebook' button.

3. In the resulting pop-up, login (as a different test user) a test user that is friends with your original test user. Authorize your application for this test user.

Now that both test users have authorized your application, you can run the above query again. This time, you should see data for that friend test user.

## Test yourself

# A note about the `/friends` edge

By this point, you should be feeling pretty familiar and confident with navigating around the Graph API. You certainly have a great foundation for further self-learning!

Let's make a quick point about the `friends` edge, which is located at `/{user-id}/friends` (or `/me/friends`). Chances are, you will be eager to use this endpoint as you play around.

Let's try it out here with your test user:

As you ran the above query, you may have noticed a few things:

* The response had a `summary` with a `total_count`, which included the number of friends that this test user has. Do you remember when you were setting up test users you made some of your test users _friends_ with other test users?
* But even if your `total_count` is a number like 2 or 3 (for example) the `data` part of the response might be an empty `[]` array or array with _one_ element.


Where is the data for these friends? If your test user has 3 friends, why is `data` empty or containing only one element?

Facebook's documentation for the friends' endpoint makes this clear:

> Only friends who have installed the app and who have granted the app the `user_friends` permission will be included. 


Remember, when creating test users, there was one test user already created by default (say `user xyz`). If the `user xyz` is friends with the test user, you will be seeing it in the `data` array. Because for `user xyz`, `user_friends` permission is included by default, and you don't need to authorize it separately. If by any chance no test user was created by default, your `data` would be empty. 

In the case of test users which you created manually, it is not enough for `test user 1` to be friends with `test user 2`. Sure, that relationship will affect the `total_count` of friends for `test user 1`, but `test user 2` also needs to _authorize its application_ to see the friends for `test user 1`.

To verify this, do the following:

1. In another tab, log out of Facebook.

2. Run the same React app with the 'Login with Facebook' button.

3. In the resulting pop-up, login (as a different test user) a test user that is friends with your original test user. Authorize your application for this test user.

Now that both test users have authorized your application, you can run the above query again. This time, you should see data for that friend test user.

# Test yourself

Understand how to use the 'friends' edge in Graph API.

__default

Know Your Friends with Graph API

A note about the `/friends` edge

Know Your Friends with Graph API

A note about the /friends edge

A note about the `/friends` edge