Clv oauth

Intro

• Get away from config for OAUTH

• Management server(less) for users

• You only have serveral things to know:

  • 1. How to get user's access token
  • 2. How to fetch user's data with access token
  • 3. Go serverless

Get started

1. How to get user's access token

• The best way to understand what's going on is to do it again step by step.

• Get you facebook app id: APP_ID, and set the application url in facebook app console

• This is your request to get your grant code

You can specify the scope

https://www.facebook.com/dialog/oauth?client_id=APP_ID&redirect_uri=REDIRECT_URI&auth_type=rerequest&scope=email,public_profile,user_friends

FYI, there are all GET method

• After you click the confirm button, facebook will redirect to your redirect_uri, and it will append GRANT_CODE after your redirect uri

REDIRECT_URI?code=GRANT_CODE

• Then, time to fetch your access token with your grant code

https://graph.facebook.com/v2.3/oauth/access_token?
    client_id=APP_ID
   &redirect_uri=REDIRECT_URI
   &client_secret=APP_SECRET
   &code=GRANT_CODE

• Finally you will receive a json response:

{
  "access_token": "ACCESS_TOKEN",
  "token_type": "bearer",
  "expires_in": 5174611,
  "auth_type": "rerequest"
}

2 Fetch user data with access token

• Fetch user's data with access token you got in the previous step

https://graph.facebook.com/me?access_token=ACCESS_TOKEN

• By default, it will only return id and name

{
    "id": "USER_ID",
    "name": "Denny Ku"
}

• But you can specify the fields that you want to know

https://graph.facebook.com/me?fields=mail,id,name&access_token=ACCESS_TOKEN

If you want to get avatar of user:

https://graph.facebook.com/v2.6/USER_ID/picture?redirect=false

And if you don't add the parameter redirect=false, you can't access the image directly:

It will response a json:

{
  "data": {
    "is_silhouette": false,
    "url": "PICTURE_URL"
  }
}

For more detail, check the official doc,

Engineer at facebook definitely make (api's) world a better place

3. Go serverless

• The most of all, you should never let the APP_SECRET expose on client side.

• Then let's break down the task of how to get your access token:

  • Send request to get the grant code

    • Access https://www.facebook.com/dialog/oauth?client_id=${clientId}&redirect_uri=${redirectUri}&auth_type=rerequest&scope=email,public_profile,user_friends

    • Then you will redirect to redirectUri with grant code(redirectUri is handled by our serverless backend)

    • Serverless backend should detect the grant code then

  • Fetch access token with grant code

Todo

• [] Facebook login

Usage

• Set variables of :

  • fb_secret

  • app_id

  • endpoint_url