Set up outgoing single sign-on on the receipt

Steps: log a new customer into your site automatically

1. 1

   In your custom receipt template, add Twig code that generates a reverse single sign-on token and URL on the customer’s first view of the receipt, only for non-guest customers.

2. 2

   Set the receipt’s continue link to point to that reverse single sign-on URL instead of your regular site.

3. 3

   On your endpoint, verify the fc_auth_token, timestamp, and fc_customer_id parameters the same way a standard single sign-on endpoint would.

4. 4

   If the token checks out, use the API to fetch the customer’s information, create or log them in on your site, and forward them on as an authenticated user.

Example: Twig code for the receipt

{% set reverse_sso_url = "" %}
{% if first_receipt_display and not is_anonymous %}
  {% set timestamp = checkout_date | date_modify("+120 seconds") | date("U") %}
  {% set reverse_sso_url = "https://www.yourwebsite.com/reversesso.php?fc_auth_token=" ~ generate_sso_token(timestamp) ~ "×tamp=" ~ timestamp ~ "&fc_customer_id=" ~ customer_id %}
  {% set continue_url = reverse_sso_url %}
{% endif %}

This only runs on the customer’s first view of the receipt, so revisiting the receipt later (from an email link) won’t trigger another redirect. generate_sso_token() takes a single timestamp argument and returns the token. customer_id is available to Twig templates automatically.

Example: verifying the token and logging the customer in

if (isset($_GET['fc_auth_token'])) {
    $fc_auth_token = $_GET['fc_auth_token'];
    $customer_id = $_GET['fc_customer_id'];
    $timestamp = $_GET['timestamp'];
}

$local_auth_token = sha1($customer_id . '|' . $timestamp . '|' . $foxycart_api_key);
$local_timestamp = date('U');

if ($fc_auth_token == $local_auth_token && $timestamp > $local_timestamp) {
    // Everything checks out, log the user in
    // Enter your logic here
}

// Redirect the customer on to your own website
header('Location: http://www.yourwebsite.com');

Example: single-click upsell on the receipt

The same token mechanism can offer a post-purchase upsell. On click (or on page load, for a fully automatic version), add a product to the cart with a JSONP request, then redirect straight to checkout with a fresh token so the transaction can complete without re-authentication:

{% if first_receipt_display == 1 and is_anonymous == 0 %}
<script>
  {% set timestamp = checkout_date | date_modify("+120 seconds") | date("U") %}
  if (!FC.json.custom_fields.upsell) {
    FC.client.request('https://' + FC.settings.storedomain + '/cart?name=Cool+Example&price=20&color=red&code=sku123&empty=reset&h:upsell=true').done(function(data) {
      var url = 'https://' + FC.settings.storedomain + '/checkout?fc_auth_token={{ generate_sso_token(timestamp) }}×tamp={{ timestamp }}&fc_customer_id={{ customer_id }}';
      window.location.href = url;
    });
  }
</script>
{% endif %}

Notes

• A guest customer can’t use single sign-on, so both examples only work for accounts, not guest checkouts, hence the is_anonymous check.

• Keep the token’s expiration short, no more than a few minutes, since it substitutes for password-based authentication.

• Only use this over an https connection, since the tokens are passed in the URL.

• To skip the Foxy receipt entirely and forward straight to your reverse single sign-on URL, replace {% set continue_url = reverse_sso_url %} with <script>window.location = ‘{{ reverse_sso_url }}’;</script>.

• To add a custom link or button pointing to your reverse single sign-on endpoint elsewhere on the receipt, reference the {{ reverse_sso_url }} Twig variable.