Based on these answers:
You can create a PHP script to change the redirect url after adding a product to the cart (by checking the product class type).
Furthermore, using the woocommerce_add_to_cart_redirect
hook you have two parameters: $url
and $adding_to_cart
(product object). Here you find the documentation.
Then:
// redirects to checkout if the product added to the cart is a subscription
add_filter( 'woocommerce_add_to_cart_redirect', 'redirect_to_checkout_if_product_is_subscription' );
function redirect_to_checkout_if_product_is_subscription( $url, $product ) {
if ( class_exists( 'WC_Subscriptions_Product' ) && WC_Subscriptions_Product::is_subscription( $product ) ) {
global $woocommerce;
$checkout_url = $woocommerce->cart->get_checkout_url();
return $checkout_url;
}
return $url;
}
The code must be added to your active theme's functions.php file.