Gravity Forms Stripe Update Default Credit Card

stripe.php

/**
 * Use with a form that has an update cc feed.  
 */
function update_default_credit_card($entry, $form) {
	if (get_user_meta( get_current_user_id(), 'stripe_customer_id', true ) !== '') {
		// Get last 4 of cc entered.  Replace with whatever entry field is your CC.
		$last4 = str_replace('X', '', $entry["8.1"]);

		// Init Stripe Client.
		try {
			// Use whatever way to get your live Secret Key.
			$stripe = new \Stripe\StripeClient(getenv('STRIPE_API_KEY'));
			$user_id = get_current_user_id();
			$customer_id = get_user_meta( $user_id, 'stripe_customer_id', true );
			// Grab all the payment methods.
			$cards = $stripe->paymentMethods->all([
				'customer' => $customer_id,
				'type' => 'card',
			]);

			// Cycle through to grab the card entered and make it the default cc.
			$data = $cards->__get('data');
			foreach ($data as $datum) {
				if ($datum instanceof Stripe\PaymentMethod) {
					$card = $datum->__get('card');
					$check = $card->__get('last4');
					// If the payment method stripe matches the one entered on the for, engage!
					if ($last4 == $check) {
						$id = $datum->__get('id');
						$stripe->customers->update(
							$customer_id,
							['invoice_settings' => ['default_payment_method' => $id]]
						);
						break;
					}
				}
			}
		}
		catch(\Exception $e) {
			$message = "!! STRIPE CC UPDATE FAILED - " . $e->getMessage();
			GFCommon::log_debug( $message );
		}
	}
}
add_action( 'gform_after_submission_42', 'update_default_credit_card', 10, 2 );