Assent.Strategy.Facebook (Assent v0.1.26) View Source

Facebook OAuth 2.0 strategy.

The Facebook user endpoint does not provide data on email verification, email is considered unverified. More here: https://developers.facebook.com/docs/facebook-login/multiple-providers#postfb1

Configuration

  • :user_url_request_fields - The fields for the resource, defaults to email,name,first_name,last_name,middle_name,link

See Assent.Strategy.OAuth2 for more.

Usage

config = [
  client_id: "REPLACE_WITH_CLIENT_ID",
  client_secret: "REPLACE_WITH_CLIENT_SECRET"
]

See Assent.Strategy.OAuth2 for more.

With JS SDK

You can use the JS SDK instead of handling it through auhorize_url/2. All you have to do is to set up you HTML page with the following way:

<fb:login-button scope="[SCOPES]" onlogin="checkLoginState();">
</fb:login-button>
<div id="status">
</div>

<script>
  function checkLoginState() {
    FB.getLoginStatus(function(response) {
      let signedRequest = response.authResponse.signedRequest
      let encodedPayload = atob(signedRequest.split('.')[1])
      let payload = JSON.parse(encodedPayload)

      window.location.href = '<%= @redirect_uri %>?&code=' + encodeURI(payload.code)
    });
  }

  window.fbAsyncInit = function() {
    FB.init({
      appId   : '[CLIENT_ID]',
      cookie  : true, // required for server to pick up session
      version : 'v6.0',
      xfbml   : true
    });
  };
</script>
<script async defer src="https://connect.facebook.net/en_US/sdk.js"></script>

In the above, the signed request is decoded and the authorization code is fetched from it. The @redirect_uri is the callback URL.

You have to use an empty redirect_uri for the callback:

{:ok, %{user: user, token: token}} =
  config
  |> Assent.Config.put(:redirect_uri, "")
  |> Assent.Strategy.Facebook.callback(params)