Make referral link to work for specific product or category of products only

If you want to restrict referral link to work only when purchasing a specific product, add a code below to functions.php file, of course, change "12345" to your product ID:

function only_specific_product($raf_info,$order,$referrer_id) {
    $items = $order->get_items();
    $enable_referral = "no";
    foreach ( $items as $item ) {
      $product_id = $item['product_id'];
      if($product_id == "12345") {
      	$enable_referral = "yes";
      }
    }
    if($enable_referral === "no") {
    	$raf_info = array("info" => "Specific product wasnt in the cart, referral wont be generated.", "generate" => "false", "increase_referrals" => "false");
    }
    return $raf_info;
}
add_filter( 'gens_raf_order_info', 'only_specific_product',10,3);

And if you want to restrict referral link to work only when purchasing a products from specific category, add a code below to functions.php file but change "12345" to your category ID:

function wpgens_only_specific_cat($raf_info,$order,$referrer_id) {
    $items = $order->get_items();
    $enable_referral = "no";
    foreach ( $items as $item ) {
      $product_id = $item['product_id'];
      $term_list = wp_get_post_terms($product_id, 'product_cat', array('fields' => 'ids'));
      if (is_array($term_list) && in_array("add_your_cat_id_here", $term_list)) {
      	$enable_referral = "yes";
      }
    }
    if($enable_referral === "no") {
    	$raf_info = array("info" => "Specific category wasnt in the cart, referral wont be generated.", "generate" => "false", "increase_referrals" => "false");
    }
    return $raf_info;
}
add_filter( 'gens_raf_order_info', 'wpgens_only_specific_cat',10,3);